Hello, dear all... 1/2*Pi = t+sum(1/2*(cos(t)/sinh(t))^(2*n)/n*sin(2*n*t)*cosh(2*n*t),n = 1 .. infinity)+sum((cos(t)/sinh(t))^(2*n-1)/(2*n-1)*sin((2*n-1)*t)*sinh((2*n-1)*t),n = 1 .. infinity) ; t in [1,2] FME