Tyma Gaidash pointed me to the Wolfram Functions site where I tried the following.
I might be missing more, but I see I'm missing the input for n. How should I add it?
So, how do we code this? the facts are we have
$M2=\sum _{n=1}^{\infty } \left(\frac{i}{\pi }\right)^{1-n}\left(\text G_{n+1,n+2}^{n+2,0}\left(^{1;\underbrace {x,…,x}_n}_{1-n,0; \underbrace {x,…,x}_n}\bigg|-\pi i\right)\right).$
and this
found here
