On this page (Exponential Function as an Infinite Product) I saw Euler's number expressed as an infinite product as
$$e=\prod_{n=1}^\infty\frac{e_n+1}{e_n}=\frac{2}{1}.\frac{5}{4}.\frac{16}{15}.\frac{65}{64}.\frac{326}{325}.\frac{1957}{1956}. ...$$
I understand the proof given on that page, but where was this formula originally mentioned? Am looking to reference it in a paper I am writing but have not found any other mention of it online. Any help pinning it down would be greatly appreciated.
