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Riemann Hypothesis is equivalent to the integral equation

$$\int_{-\infty}^{\infty} \frac{\log \mid \zeta (1/2+it)\mid }{1+4t^2} \ dt =0$$

Many other integral equations exist that are equivalent.

How to show that they are equivalent ?

They usually include absolute value of a function.

Why is that ?

I assume it came from a contour integral on the riemann sphere.

The growth rate of the zeta function on the critical line also probably relates to all those integrals , not ?

Another example is

Establishing the exact value $$\int_{0}^{\infty}\frac{(1-12t^2)}{(1+4t^2)^3}\int_{1/2}^{\infty}\log|\zeta(\sigma+it)|~d\sigma ~dt=\frac{\pi(3-\gamma)}{32}$$ is equivalent to the Riemann Hypothesis.

More examples :

Riemann's Hypothesis is true if and only if $$\frac{1}{\pi}\int_0^{\infty} \log\left|\frac{\zeta(\frac{1}{2}+it)}{\zeta(\frac{1}{2})}\right|\ \frac{dt}{t^2}=\frac{\pi}{8}+\frac{\gamma}{4}+\frac{\log 8\pi}{4}-2$$

Take $a\in R$ with $\frac{1}{2}\leq a<1$. Riemann's $\zeta$-function has no zeros in $\Re(s)>a$ if and only if $$\frac{1}{\pi}\int_0^{\infty} \log\left|\frac{\zeta(a+it)}{\zeta(a)}\right|\ \frac{dt}{t^2}=\frac{\zeta'(a)}{2\zeta(a)}-\frac{1}{1-a}$$

And many more exist.

I have no idea how to get to such conclusions or prove them.

Im not even sure how to prove integrals for "slightly easier" cases , meaning not famous open problems but zero's of other nontrivial functions that are not on a half-plane.

mick
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  • Note that $\log|z|=\mathrm{Re}(\log(z))$ – robjohn Aug 01 '21 at 23:42
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    The first equivalence is due to balazard and saias (original proof comes from Jensen applied to a transform of zeta using the mobius map that bends the critical line into the unit circle and sends the right half plane to the interior; bui and others gave a proof using cauchy and basic rz estimates; very popular topic here on mse; for the more general integral equivalences, will strongly recommend broughan's tomes on the subject, especially volume 2 – Conrad Aug 02 '21 at 00:46
  • As a heuristic $\int_{-\infty}^{\infty} \frac{\log \mid \zeta (1/2+it)\mid }{1+4t^2} \ dt \ge 0$ (for example because in Jensen formula the extra terms that come from zeroes is always non-negative), while the integral is most negative precisely around the critical line zeroes, so it makes sense that the integral will be minimal when there are the most possible critical line zeroes which is RH – Conrad Aug 02 '21 at 04:22
  • I suspect that a solution to those integrals will involve a sum over the Riemann zeta zeros. – Mats Granvik Aug 04 '21 at 20:11
  • Let the numbers 4 and 3 be replaced by infinity, and you might have a starting point for approximating the integral: Integrate[Log[Sum[(E^(Round[Log[n]*4]/4))^(x), {n, 1, 3}]],x] in Wolfram Alpha And modify the integral approximation to include analytic continuation of the Riemann zeta function. See also: https://math.stackexchange.com/a/4216806/8530 – Mats Granvik Aug 05 '21 at 12:09
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    The idea is one integrates along a rectangular contour in the critical strip. If there was a hypothetical zero off the critical line, one would expect to detect its log singularity contribution as a jump in argument and this would change the value of the contour integral. – KStar Dec 08 '24 at 15:12
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    The full expression for the first type of integral of integral you posted is $$\frac{a}{\pi}\int_{-\infty}^{\infty}\frac{\log|\zeta(b+it)|}{a^2+t^2}dt=\log\left|\frac{\zeta(a+b)(a+b-1)}{a-b+1}\right|+\sum_{\sigma_k > b}\log\left|\frac{a+\sigma_k-b+it_k}{a-\sigma_k+b-it_k}\right|.$$ The sum vanishing for $b=\frac{1}{2}$ is RH. – KStar Dec 08 '24 at 15:18
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    @KStar +1 BUT do you have a source ? – mick Dec 11 '24 at 14:28
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    @mick See here, here, and here. For Volchkov’s integral, see here. FWIW attempting to prove RH through these integral approaches is essentially futile: one has to be careful of things like log singularities or arg jumps (this essentially breaks using IBP), uniform convergence (this essentially breaks swapping integral reps), sufficiently strong unconditional bounds etc. – KStar Dec 11 '24 at 17:04
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    TL;DR, you integrate along a rectangular contour ranging from some $\varepsilon>0$ to the right of $\Re(s)=\frac{1}{2}$, and go to $\Re(s)=1$, doing a small semicircular indent around the simple pole at $s=1$ staying within the critical strip say. You then consider what happens when $\varepsilon\to 0^+$. – KStar Dec 11 '24 at 17:06

2 Answers2

5

A long comment on the Riemann hypothesis equivalent by V.V.Volchkov found here:

$$\int_{0}^{\infty}\frac{(1-12t^2)}{(1+4t^2)^3}\int_{1/2}^{\infty}\log|\zeta(\sigma+it)|~d\sigma ~dt = \frac{\pi(3-\gamma)}{32} \label{1}\tag{1}$$

mentioned here.

I cannot give you the absolute correct answer but what I can give you is a plausibility argument in the form of a slightly incorrect calculation of the integral yielding the answers:

$$\int_{0}^{\infty}\frac{(1-12t^2)}{(1+4t^2)^3}\int_{1/2}^{\infty}\log|\zeta(\sigma+it)|~d\sigma ~dt=-\frac{\pi (1-2 \gamma )}{32}\color{Blue}{-\frac{\pi}{32} \sum _{k=2}^{\infty } \frac{1}{k}} \label{2}\tag{2}$$

and

$$\int_{0}^{\infty}\frac{(1-12t^2)}{(1+4t^2)^3}\int_{1/2}^{\infty}\log|\zeta(\sigma+it)|~d\sigma ~dt=\frac{\pi(3-3\gamma)}{32} \label{2.1}\tag{2.1}$$

instead.

The starting points are \eqref{3} to \eqref{8} for results regarding the von Mangoldt function which have been proven by joriki (see here) and GH from MO (see here): assuming that $n>1$:

$$\Lambda(n)=\lim\limits_{s \rightarrow 1} \zeta(s)\sum\limits_{d|n} \frac{\mu(d)}{d^{(s-1)}} \label{3}\tag{3}$$ $$\begin{align} a(n) &=-2\lim\limits_{s \rightarrow 0} \zeta(s)\sum\limits_{d|n} \frac{\mu(d)}{d^{(s-1)}} \label{4}\tag{4} \\ &= \sum\limits_{d|n} d \cdot \mu(d) \label{5}\tag{5} \\ \end{align}$$

$$T = \left( \begin{array}{ccccccc} \color{Red}{+1}&\color{Blue}{+1}&\color{Blue}{+1}&\color{Blue}{+1}&\color{Blue}{+1}&\color{Blue}{+1}&\color{Blue}{+1}&\color{Blue}{\cdots} \\ \color{Red}{+1}&-1&+1&-1&+1&-1&+1 \\ \color{Red}{+1}&+1&-2&+1&+1&-2&+1 \\ \color{Red}{+1}&-1&+1&-1&+1&-1&+1 \\ \color{Red}{+1}&+1&+1&+1&-4&+1&+1 \\ \color{Red}{+1}&-1&-2&-1&+1&+2&+1 \\ \color{Red}{+1}&+1&+1&+1&+1&+1&-6 \\ \color{Red}{\vdots}&&&&&&&\ddots \end{array} \right) \label{6}\tag{6}$$

$$\displaystyle \begin{pmatrix} \color{Red}{\frac{T(1,1)}{1 \cdot 1}}&\color{Blue}{+\frac{T(1,2)}{1 \cdot 2}}&\color{Blue}{+\frac{T(1,3)}{1 \cdot 3}+}&\color{Blue}{\cdots}&\color{Blue}{+\frac{T(1,k)}{1 \cdot k}} \\ \color{Red}{\frac{T(2,1)}{2 \cdot 1}}&+\frac{T(2,2)}{2 \cdot 2}&+\frac{T(2,3)}{2 \cdot 3}+&\cdots&+\frac{T(2,k)}{2 \cdot k} \\ \color{Red}{\frac{T(3,1)}{3 \cdot 1}}&+\frac{T(3,2)}{3 \cdot 2}&+\frac{T(3,3)}{3 \cdot 3}+&\cdots&+\frac{T(3,k)}{3 \cdot k} \\ \color{Red}{\vdots}&\vdots&\vdots&\ddots&\vdots \\ \color{Red}{\frac{T(n,1)}{n \cdot 1}}&+\frac{T(n,2)}{n \cdot 2}&+\frac{T(n,3)}{n \cdot 3}+&\cdots&+\frac{T(n,k)}{n \cdot k} \end{pmatrix} = \begin{pmatrix} \color{Blue}{\frac{\infty}{1}} \\ +\frac{\Lambda(2)}{2} \\ +\frac{\Lambda(3)}{3} \\ \vdots \\ +\frac{\Lambda(n)}{n} \end{pmatrix} \label{7}\tag{7}$$ $$=\;\;\;\;\;\;\;\;\;\;\;$$ $$\displaystyle \begin{pmatrix} \color{Red}{\frac{\infty}{1}}&+\frac{\Lambda(2)}{2}&+\frac{\Lambda(3)}{3}+&\cdots&+\frac{\Lambda(k)}{k} \end{pmatrix}\;\;\;\;\;\;\;\;\;\;\; \label{8}\tag{8}$$

The following limits and integrals can be done in Mathematica 14:

$$\begin{align} \sum\limits_{n=1}^{\infty}\sum\limits_{k=1}^{\infty} \frac{T(n,k)}{n^c \cdot k^s} &= \sum\limits_{n=1}^{\infty}\sum\limits_{k=1}^{\infty} \frac{a(\gcd(n,k))}{n^c \cdot k^s} \label{9}\tag{9} \\ &=\sum\limits_{n=1}^{\infty} \frac{\lim\limits_{z \rightarrow s} \zeta(z)\sum\limits_{d|n} \frac{\mu(d)}{d^{(z-1)}}}{n^c} \label{10}\tag{10}\\ &= \frac{\zeta(s) \zeta(c)}{\zeta(s + c - 1)} \label{11}\tag{11}\\ \end{align}$$

$$\begin{align} \frac{\zeta '(s)}{\zeta (s)}&=\lim_{c\to 1} \, \left( \color{Red}{\zeta (c)}-\frac{\zeta (s) \zeta (c)}{\zeta (s+c-1)}\right) \label{12}\tag{12}\\ &=\sum\limits_{n=1}^{\infty} \left( \color{Red}{\frac{1}{n^{1}}}-\frac{\lim\limits_{z \rightarrow s} \zeta(z)\sum\limits_{d|n} \frac{\mu(d)}{d^{(z-1)}}}{n^{1}}\right) \label{13}\tag{13} \\ &= \sum\limits_{n=1}^{\infty}\left(\color{Red}{\frac{1}{n^{1}}}-\sum\limits_{k=1}^{\infty} \frac{a(\gcd(n,k))}{n^{1} \cdot k^s}\right) \label{14}\tag{14} \\ &= \sum\limits_{n=1}^{\infty}\left(\sum\limits_{k=2}^{\infty} \frac{a(\gcd(n,k))}{n^{1} \cdot k^s}\right) \label{15}\tag{15} \\ &= \sum\limits_{n=1}^{\infty}\sum\limits_{k=1}^{\infty} \color{Red}{[k>1]}\frac{a(\gcd(n,k))}{n^{1} \cdot k^s} \label{16}\tag{16} \\ \end{align}$$

$$[k>1] = \text{Iverson bracket} = (\text{If k > 1 then 1 else 0}) \label{17}\tag{17} $$

$$\begin{align}\log | \zeta (\sigma+i t)| &=\log (| \zeta (\sigma+i t)| ) \label{18}\tag{18} \\ &=\frac{1}{2} \log (\zeta (\sigma+i t))+\frac{1}{2} \log (\zeta (\sigma-i t)) \label{19}\tag{19} \\ &=\int \frac{1}{2} \left(\frac{\zeta '(\sigma+i t)}{\zeta (\sigma+i t)}+\frac{\zeta '(\sigma-i t)}{\zeta (\sigma-i t)}\right) \, d\sigma \label{20}\tag{20} \\ &=\int \frac{1}{2} \left(\sum\limits_{n=1}^{\infty}\sum\limits_{k=1}^{\infty} \color{Red}{[k>1]}\frac{a(\gcd(n,k))}{n^{1} \cdot k^{\sigma+i t}}+\sum\limits_{n=1}^{\infty}\sum\limits_{k=1}^{\infty} \color{Red}{[k>1]}\frac{a(\gcd(n,k))}{n^{1} \cdot k^{\sigma-i t}}\right) \, d\sigma \label{21}\tag{21} \\ &=\int \frac{1}{2} \left(\sum\limits_{n=1}^{\infty}\sum\limits_{k=1}^{\infty} \color{Red}{[k>1]} \left(\frac{a(\gcd (n,k))}{n^{1} \cdot k^{\sigma+i t}}+\frac{a(\gcd (n,k))}{n^{1} \cdot k^{\sigma-i t}}\right)\right) \, d\sigma \label{22}\tag{22}\\ &=\sum\limits_{n=1}^{\infty}\sum\limits_{k=1}^{\infty} \int \frac{1}{2} \color{Red}{[k>1]} \left(\frac{a(\gcd (n,k))}{n^{1} \cdot k^{\sigma+i t}}+\frac{a(\gcd (n,k))}{n^{1} \cdot k^{\sigma-i t}}\right) \, d\sigma \label{23}\tag{23}\\ &=\sum\limits_{n=1}^{\infty}\sum\limits_{k=1}^{\infty} \color{Red}{[k>1]}-\frac{\left(1+k^{2 i t}\right) k^{-\sigma-i t} a(\gcd (k,n))}{2 n \log (k)} \label{24}\tag{24} \\ \end{align}$$

$$\begin{align} \int_{1/2}^{\infty}\log|\zeta(\sigma+it)|~d\sigma &=\int_{\frac{1}{2}}^{\infty }\sum\limits_{n=1}^{\infty}\sum\limits_{k=1}^{\infty} \color{Red}{[k>1]}-\frac{\left(1+k^{2 i t}\right) k^{-\sigma-i t} a(\gcd (k,n))}{2 n \log (k)} \, d\sigma \label{25}\tag{25} \\ &=\sum\limits_{n=1}^{\infty}\sum\limits_{k=1}^{\infty} \int_{\frac{1}{2}}^{\infty } \color{Red}{[k>1]}-\frac{\left(1+k^{2 i t}\right) k^{-\sigma-i t} a(\gcd (k,n))}{2 n \log (k)} \, d\sigma \label{26}\tag{26} \\ &=\sum\limits_{n=1}^{\infty}\sum\limits_{k=1}^{\infty} \color{Red}{[k>1]}-\frac{k^{-\frac{1}{2}-i t} \left(1+k^{2 i t}\right) a(\gcd (k,n))}{2 n \log ^2(k)} \label{27}\tag{27} \\ \end{align}$$

except for this integral which can not be done in Mathematica 14:

$$\begin{align} \int_{0}^{\infty}\frac{(1-12t^2)}{(1+4t^2)^3}\int_{1/2}^{\infty}\log|\zeta(\sigma+it)|~d\sigma ~dt &=\int_{0}^{\infty}\frac{(1-12t^2)}{(1+4t^2)^3}\sum\limits_{n=1}^{\infty}\sum\limits_{k=1}^{\infty} \color{Red}{[k>1]}-\frac{k^{-\frac{1}{2}-i t} \left(1+k^{2 i t}\right) a(\gcd (k,n))}{2 n \log ^2(k)} \, dt \label{28}\tag{28} \\ &=\sum\limits_{n=1}^{\infty}\sum\limits_{k=1}^{\infty} \int_{0}^{\infty}\frac{(1-12t^2)}{(1+4t^2)^3}\color{Red}{[k>1]}-\frac{k^{-\frac{1}{2}-i t} \left(1+k^{2 i t}\right) a(\gcd (k,n))}{2 n \log ^2(k)} \, dt \label{29}\tag{29} \\ \end{align}$$

Therefore we resort to computing instances of the integral above for integer values between $1$ and $6$ for both $n$ and $k$. That is: $$n=1,2,3,4,5,6 \label{30}\tag{30} $$ and $$k=1,2,3,4,5,6 \label{31}\tag{31} $$, with the following Mathematica 14 program:

Clear[sigma, t, a, n, k, B] (*takes several minutes to run*)
nn = 6;(* nn=3 for faster program but smaller matrix *)
a[n_] := Total[MoebiusMu[Divisors[n]]*Divisors[n]]
TableForm[
 B = Integrate[(1 - 12*t^2)/(1 + 4*t^2)^3*
    Integrate[
     Integrate[
      Table[Table[
        If[k > 1, (a[GCD[n, k]]/n/k^(sigma + I*t) + 
            a[GCD[n, k]]/n/k^(sigma - I*t))/2, 0], {k, 1, nn}], {n, 1,
         nn}], sigma], {sigma, 1/2, Infinity}], {t, 0, Infinity}]]
TableForm[1/(-(Pi/32))*B]
TableForm[
 1/(-(Pi/32))*Table[Table[B[[n, k]]*n*k, {k, 1, nn}], {n, 1, nn}]]
-(Pi/32)*
 Limit[Zeta[s]*Zeta[s]/Zeta[s + s - 1] - Zeta[s] - (Zeta[s] - 1), 
  s -> 1]
N[%, 40]

The first output from the program is matrix $B$ that has the definition:
$$B(n,k)=\int_0^{\infty } \frac{\left(1-12 t^2\right) \int_{\frac{1}{2}}^{\infty } \left(\int \left[k>1\right] \frac{1}{2} \left(\frac{a(\gcd (n,k))}{n k^{\sigma+i t}}+\frac{a(\gcd (n,k))}{n k^{\sigma-i t}}\right) \, d\sigma\right) \, d\sigma}{\left(4 t^2+1\right)^3} \, dt \label{32}\tag{32} $$

and starts:

$$B=\left( \begin{array}{cccccc} \color{Red}{0} & \color{Blue}{-\frac{\pi }{64}} & \color{Blue}{-\frac{\pi }{96}} & \color{Blue}{-\frac{\pi }{128}} & \color{Blue}{-\frac{\pi }{160}} & \color{Blue}{-\frac{\pi }{192}} \label{33}\tag{33} \\ \color{Red}{0} & \frac{\pi }{128} & -\frac{\pi }{192} & \frac{\pi }{256} & -\frac{\pi }{320} & \frac{\pi }{384} \\ \color{Red}{0} & -\frac{\pi }{192} & \frac{\pi }{144} & -\frac{\pi }{384} & -\frac{\pi }{480} & \frac{\pi }{288} \\ \color{Red}{0} & \frac{\pi }{256} & -\frac{\pi }{384} & \frac{\pi }{512} & -\frac{\pi }{640} & \frac{\pi }{768} \\ \color{Red}{0} & -\frac{\pi }{320} & -\frac{\pi }{480} & -\frac{\pi }{640} & \frac{\pi }{200} & -\frac{\pi }{960} \\ \color{Red}{0} & \frac{\pi }{384} & \frac{\pi }{288} & \frac{\pi }{768} & -\frac{\pi }{960} & -\frac{\pi }{576} \\ \end{array} \right) $$

Dividing this matrix $B$ with: $$-\frac{\pi}{32} \label{34}\tag{34}$$

$$\left( \begin{array}{cccccc} \color{Red}{0} & \color{Blue}{\frac{1}{2}} & \color{Blue}{\frac{1}{3}} & \color{Blue}{\frac{1}{4}} & \color{Blue}{\frac{1}{5}} & \color{Blue}{\frac{1}{6}} \\ \color{Red}{0} & -\frac{1}{4} & \frac{1}{6} & -\frac{1}{8} & \frac{1}{10} & -\frac{1}{12} \\ \color{Red}{0} & \frac{1}{6} & -\frac{2}{9} & \frac{1}{12} & \frac{1}{15} & -\frac{1}{9} \\ \color{Red}{0} & -\frac{1}{8} & \frac{1}{12} & -\frac{1}{16} & \frac{1}{20} & -\frac{1}{24} \\ \color{Red}{0} & \frac{1}{10} & \frac{1}{15} & \frac{1}{20} & -\frac{4}{25} & \frac{1}{30} \\ \color{Red}{0} & -\frac{1}{12} & -\frac{1}{9} & -\frac{1}{24} & \frac{1}{30} & \frac{1}{18} \\ \end{array}\right) \label{35}\tag{35}$$

Multiplying matrix $B$ with $$-\frac{n k B(n,k)}{\frac{\pi }{32}} \label{36}\tag{36}$$

$$\left( \begin{array}{cccccc} \color{Red}{0} & \color{Blue}{1} & \color{Blue}{1} & \color{Blue}{1} & \color{Blue}{1} & \color{Blue}{1} \\ \color{Red}{0} & -1 & 1 & -1 & 1 & -1 \\ \color{Red}{0} & 1 & -2 & 1 & 1 & -2 \\ \color{Red}{0} & -1 & 1 & -1 & 1 & -1 \\ \color{Red}{0} & 1 & 1 & 1 & -4 & 1 \\ \color{Red}{0} & -1 & -2 & -1 & 1 & 2 \\ \end{array} \right) \label{37}\tag{37}$$

Compare this modified matrix $B$ to matrix $T$:

$$T = \left( \begin{array}{ccccccc} \color{Red}{+1}&\color{Blue}{+1}&\color{Blue}{+1}&\color{Blue}{+1}&\color{Blue}{+1}&\color{Blue}{+1}&\color{Blue}{+1}&\color{Blue}{\cdots} \\ \color{Red}{+1}&-1&+1&-1&+1&-1&+1 \\ \color{Red}{+1}&+1&-2&+1&+1&-2&+1 \\ \color{Red}{+1}&-1&+1&-1&+1&-1&+1 \\ \color{Red}{+1}&+1&+1&+1&-4&+1&+1 \\ \color{Red}{+1}&-1&-2&-1&+1&+2&+1 \\ \color{Red}{+1}&+1&+1&+1&+1&+1&-6 \\ \color{Red}{\vdots}&&&&&&&\ddots \end{array} \right) \label{38}\tag{38}$$

They look like they are the same.

Subtracting the numbers in red and blue and forming matrix $A$:

$$A=\left( \begin{array}{cccccc} \color{Red}{0} & \color{Blue}{0} & \color{Blue}{0} & \color{Blue}{0} & \color{Blue}{0} & \color{Blue}{0} \\ \color{Red}{0} & \frac{\pi }{128} & -\frac{\pi }{192} & \frac{\pi }{256} & -\frac{\pi }{320} & \frac{\pi }{384} \\ \color{Red}{0} & -\frac{\pi }{192} & \frac{\pi }{144} & -\frac{\pi }{384} & -\frac{\pi }{480} & \frac{\pi }{288} \\ \color{Red}{0} & \frac{\pi }{256} & -\frac{\pi }{384} & \frac{\pi }{512} & -\frac{\pi }{640} & \frac{\pi }{768} \\ \color{Red}{0} & -\frac{\pi }{320} & -\frac{\pi }{480} & -\frac{\pi }{640} & \frac{\pi }{200} & -\frac{\pi }{960} \\ \color{Red}{0} & \frac{\pi }{384} & \frac{\pi }{288} & \frac{\pi }{768} & -\frac{\pi }{960} & -\frac{\pi }{576} \\ \end{array} \right) \label{39}\tag{39}$$

Since the conjectured formula for matrix $B$ is:

$$B(n,k) = -\frac{\pi a(\gcd (n,k))}{32 n k} \label{40}\tag{40}$$

and given that the matrix in display \eqref{37} is essentially matrix $T$ in displays \eqref{38} and \eqref{6}, then matrix $A$ is known to have the generating function and limit:

$$\begin{align} \sum _{n=1}^{\infty } \left(\sum _{k=1}^{\infty } \frac{A(n,k)}{k^s n^s}\right) &=-\frac{\pi}{32} \underset{s\to 1}{\text{lim}}\left(\frac{\zeta (s) \zeta (s)}{\zeta (s+s-1)}-\color{Red}{\zeta (s)}-\color{Blue}{(\zeta (s)-1)}\right) \label{41}\tag{41} \\ &=-\frac{\pi (1-2 \gamma )}{32} \label{42}\tag{42} \\ \end{align}$$

Since: $$-\frac{\pi}{32} \underset{s\to 1}{\text{lim}}\left(\color{Blue}{(\zeta (s)-1)}\right) = \color{Blue}{-\frac{\pi}{32} \sum _{k=2}^{\infty } \frac{1}{k}} \label{43}\tag{43}$$

we get the wrong answer:

$$\int_{0}^{\infty}\frac{(1-12t^2)}{(1+4t^2)^3}\int_{1/2}^{\infty}\log|\zeta(\sigma+it)|~d\sigma ~dt=-\frac{\pi (1-2 \gamma )}{32}\color{Blue}{-\frac{\pi}{32} \sum _{k=2}^{\infty } \frac{1}{k}} \label{44}\tag{44}$$

compared to V.V.Volchov:

$$\int_{0}^{\infty}\frac{(1-12t^2)}{(1+4t^2)^3}\int_{1/2}^{\infty}\log|\zeta(\sigma+it)|~d\sigma ~dt = \frac{\pi(3-\gamma)}{32} \label{45}\tag{45}$$

It is hard for me to tell exactly what I did wrong, but I am pretty sure it is a matter of analytic continuation that I don't know how to deal with. Unless also V.V.Volchov was slightly wrong regarding the resulting pole in blue, but I don't know about that because I have not read his paper.


Edit 9.11.2024:

Mathematica 14 for the comment below:

Clear[s, sigma, t]

int = Integrate[1/7^(s - 1)/(s - 1), s]

s = sigma + I*t v = int

Integrate[(ExpIntegralEi[-((-1 + sigma + I t) Log[7])] + ExpIntegralEi[-((-1 + sigma - I t) Log[7])])/2, {sigma, 1/2, Infinity}]

Integrate[ 1/4 ((1 - 2 I t) ExpIntegralEi[ 1/2 (1 - 2 I t) Log[7]] + (1 + 2 I t) ExpIntegralEi[ 1/2 (1 + 2 I t) Log[7]] - (2 7^(1/2 - I t) (1 + 7^(2 I t)))/ Log[7])(1 - 12t^2)/(1 + 4*t^2)^3, {t, 0, Infinity}]

Clear[k, m] Limit[1/32 [Pi] (1 + Log[m]) - Pi/32*Sum[1/k, {k, 2, m}], m -> Infinity]

where seven plays the role of $m$

It is possible to get rid of the sum

$$\color{Blue}{-\frac{\pi}{32} \sum _{k=2}^{\infty } \frac{1}{k}} \label{46}\tag{46}$$

in blue, if one is allowed the following:

Continuing from display \eqref{43}: The indefinite integral of the analytic continuation of the sum in blue is:

$$\color{Blue}{\int \zeta (s)-1 \, ds=\int \underset{m\to \infty }{\text{lim}}\left(\sum _{k=2}^m \frac{1}{k^s}+\frac{1}{(s-1) m^{s-1}}\right) \, ds} \label{47}\tag{47}$$

$$\color{Blue}{=-\sum _{k=2}^m \frac{k^{-s}}{\log (k)}+\text{Ei}(-((s-1) \log (m)))} \label{48}\tag{48}$$

Substituting:

$$s=\sigma+i t \label{49}\tag{49}$$

and integrating the real part of $\color{Blue}{\text{Ei}(-((s-1) \log (m)))}$: $$\color{Blue}{\int_{\frac{1}{2}}^{\infty } \frac{1}{2} (\text{Ei}(-((\sigma+i t-1) \log (m)))+\text{Ei}(-((\sigma-i t-1) \log (m)))) \, d\sigma=\frac{1}{4} \left((1+2 i t) \text{Ei}\left(\frac{1}{2} (2 i t+1) \log (m)\right)+(1-2 i t) \text{Ei}\left(\frac{1}{2} (1-2 i t) \log (m)\right)-\frac{2 \left(1+m^{2 i t}\right) m^{\frac{1}{2}-i t}}{\log (m)}\right)} \label{50}\tag{50}$$

Integrating again: $$\color{Blue}{\int_0^{\infty } \frac{\left(1-12 t^2\right) \left((1+2 i t) \text{Ei}\left(\frac{1}{2} (2 i t+1) \log (m)\right)+(1-2 i t) \text{Ei}\left(\frac{1}{2} (1-2 i t) \log (m)\right)-\frac{2 \left(1+m^{2 i t}\right) m^{\frac{1}{2}-i t}}{\log (m)}\right)}{4 \left(4 t^2+1\right)^3} \, dt} \label{51}\tag{51}$$

we get the answer:

$$\color{Blue}{=\frac{1}{32} \pi (\log (m)+1)} \label{52}\tag{52}$$

plugging \eqref{52} into \eqref{46}:

$$\color{Blue}{-\frac{\pi}{32} \sum _{k=2}^{\infty } \frac{1}{k}} \label{53}\tag{53}$$

$$\color{Blue}{\underset{m\to \infty }{\text{lim}}\left(\frac{1}{32} \pi (\log (m)+1)-\frac{1}{32} \pi \sum _{k=2}^m \frac{1}{k}\right)=-\frac{1}{32} (\gamma -2) \pi} \label{54}\tag{54}$$

Taking the black part of the right hand side of \eqref{2} and substituting the blue part of \eqref{2} with the right hand side of \eqref{54}:

$$\frac{1}{32} \pi (1-2 \gamma )\color{Blue}{-\frac{1}{32} (\gamma -2) \pi} =\frac{\pi(3-3\gamma)}{32} \label{55}\tag{55}$$

we get the less incorrect answer:

$$\int_{0}^{\infty}\frac{(1-12t^2)}{(1+4t^2)^3}\int_{1/2}^{\infty}\log|\zeta(\sigma+it)|~d\sigma ~dt=\frac{\pi(3-3\gamma)}{32} \label{56}\tag{56}$$

compared to V.V.Volchov:

$$\int_{0}^{\infty}\frac{(1-12t^2)}{(1+4t^2)^3}\int_{1/2}^{\infty}\log|\zeta(\sigma+it)|~d\sigma ~dt = \frac{\pi(3-\gamma)}{32} \label{57}\tag{57}$$


Edit 10.11.2024:

Mathematica 14:

nn = 10^3;
NIntegrate[(1 - 12*t^2)/(1 + 4*t^2)^3*
  NIntegrate[Log[Abs[Zeta[sigma + I*t]]], {sigma, 1/2, 9*nn}], {t, 0, nn}]

gives:

0.237853...

while:

N[Pi*(3 - EulerGamma)/32]

gives:

0.237856...

which numerically supports V.V.Volchov's number $$\frac{\pi(3-\gamma)}{32}=0.237856...\text{=probably right}$$ in displays \eqref{1}, \eqref{45} and \eqref{57} being probably right, while my number $$\frac{\pi(3-3\gamma)}{32}=0.12452...\text{=probably wrong}$$ in displays \eqref{2.1} and \eqref{56} is probably wrong.

Mats Granvik
  • 7,614
  • 3
    I do not understand your computations in the critical strip where $\log \zeta$ is large but it is fairly easy to show that $\int_{1/2}^{\infty}\log|\zeta(\sigma+it)|~d\sigma =O(\log |t|), t \ge t_0$ which makes the double integral absolutely convergent regardless of RH - the factor $\frac{1-12t^2}{(1+4t^2)^3}$ is just (a scaling of) the second derivative of $\frac{1}{1+4t^2}$ and the equivalence is just a clever rewriting of the known sum of inverse of roots (as an inequality which becomes equality iff RH) so has little content - the OP equality equivalence is more difficult to prove – Conrad Oct 29 '24 at 15:55
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    I appreciate your answer, but I really wish you used an open source, free, math program instead of a closed source, paid one, where only elite fellows to the program may follow along with your answer. Mathematica 14 is not free software and is not open source, so installing it on your machine could leak in the worst case your entire net worth of cryptocurrency for example, as arbitrary code running on your machine may occasionally do, so I plead you to give your code examples in the future in an open source language that does the same thing, such as Octave or Maple. – Snared Nov 10 '24 at 16:04
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    note that any deviation from the conjectured value $\frac{\pi(3-\gamma)}{32}$ is extremely small even if RH is false since it depends on the (sum of) discrepancies $2f_{\gamma}(1/2)-f_{\gamma}(\beta)-f_{\gamma}(1-\beta)$ at noncritical line roots where $f_{\gamma}(\beta)=\frac{\beta}{\beta^2+\gamma^2}$ so of order at most $\gamma^{-2}$ for the first noncritical line root - since all the roots up to $\gamma$ very large are known to be on the critical line, said diference is going very small - as of now at most of order some $10^{-24}$ since RH has been verified up to $3 \times 10^{-12}$ – Conrad Nov 10 '24 at 16:21
0

The right hand side of display $(54)$ in the other answer:

$$\color{Blue}{\underset{m\to \infty }{\text{lim}}\left(\frac{1}{32} \pi (\log (m)+1)-\frac{1}{32} \pi \sum _{k=2}^m \frac{1}{k}\right)=-\frac{1}{32} (\gamma -2) \pi}$$

$$\int_{0}^{\infty}\frac{(1-12t^2)}{(1+4t^2)^3}\int_{1/2}^{\infty}\Re\left(\left.\int(\zeta(s)-1)~ds\right|_{s=\sigma+it}\right)~d\sigma ~dt = \color{Blue}{\frac{\pi(2-\gamma)}{32}}$$

is not far from display $(1)$:

$$\int_{0}^{\infty}\frac{(1-12t^2)}{(1+4t^2)^3}\int_{1/2}^{\infty}\Re\left(\left.\int\frac{\zeta'(s)}{\zeta(s)}~ds\right|_{s=\sigma+it}\right)~d\sigma ~dt = \frac{\pi(3-\gamma)}{32}$$

Mathematica 14:

Clear[m, s, d, sigma, t]
m = 7;
d = 11;

int1 = Integrate[1/m^s, s]; int2 = Integrate[1/d^(s - 1)/(s - 1), s];

s = sigma + I*t; v1 = int1; w1 = int2;

s = sigma - I*t; v2 = int1; w2 = int2;

inte1 = Integrate[(v1 + v2)/2, {sigma, 1/2, Infinity}]; inte2 = Integrate[(w1 + w2)/2, {sigma, 1/2, Infinity}];

Integrate[inte1(1 - 12t^2)/(1 + 4*t^2)^3, {t, 0, Infinity}] Integrate[inte2(1 - 12t^2)/(1 + 4*t^2)^3, {t, 0, Infinity}]

Mats Granvik
  • 7,614
  • https://oeis.org/A384541 Decimal expansion of (1/32)(2 - gamma)Pi, where gamma is the Euler-Mascheroni constant. https://oeis.org/A215722 Decimal expansion of Pi*(3 - gamma)/32, where gamma is Euler's constant A001620. – Mats Granvik Jun 07 '25 at 10:29