Hello... log(2)=2*sum(((-1)^(n+1)*cosh(Pi*n))/((sqrt(cosh(Pi)^2+1)+cosh(Pi))^n*n),n=1..infinity); for all t log(2)=2*sum(((-1)^(n+1)*cosh(n*t))/(n*(sqrt(cosh(t)^2+1)+cosh(t))^n),n=1..infinity);