Nice-calculus-evaluate-S-n-1-2-2n-1-cos-pi-2-n-M-N-1970-

Question Number 120875 by mnjuly1970 last updated on 03/Nov/20

\dots N i c e c a l c u l u s \dots

e v a l u a t e ::

S = \underset{n = 1}{\sum^{\infty}} (\frac{2^{- 2 n}}{1 + c o s (\frac{π}{2^{n}})}) = ? ?

\dots M . N . 1970 \dots