Expansion of Sum_{n>=0} ( (1+x)^n/(1-x)^n + (1-x)^n/(1+x)^n )^n / 4^n, listing the coefficients of only the even powers of x.

A369089

Expansion of Sum_{n>=0} ( (1+x)^n/(1-x)^n + (1-x)^n/(1+x)^n )^n / 4^n, listing the coefficients of only the even powers of x.