I wanted to evaluate the following sum psi(2n+1)/(2n+1)-psi(2n)/(2n) where n ranges from 1 to infinity and psi is the Chebyshev second function. So I wrote the following code.
Hi. There appears to be some characters missing from your code. As it is right now, the code doesn’t work and is missing the range for the outer summation.
If Mathematica doesn’t return a result, then this often means that a symbolic value for the sum doesn’t exist. Are you certain that a symbolic value exists? If not, you may want to use NSum to try finding a numeric estimation.