I'm trying to use the Pohlig-Hellman algorithm to solve for $x$ where $15^x=131(\bmod 337)$. This is what I have so far:
prime factors of p-1: $336=2^4*3*7$
$q=2: x=2^0*x_0+2^1*x_1+2^2*x_2+2^3*x_3$
$x_0$: $131^{168}=15^{168*x_0}$, $-1(\bmod 337) = (-1)^{x_0}(\bmod 337)$, $x_0=1$
$x_1:$ $131*15^{-(1)}=131*45=166(\bmod 337)$, $166^{184}=15^{168*x_1}$, $148(\bmod 337)=-1^{x_1}(\bmod 337)$
However, from there, $x_1$ has no answer. So I know I've done something wrong, I just don't see what. I've double and triple checked every computation, so I assume I misunderstand something about the algorithm.
