So recently I've been working through some challenge problems from my old calculus textbook for fun. I'm stuck on one of the integrals, though, and can't find any solutions online. This isn't for homework...it's for my interest and hopefully the interest of others. Here it is (sorry about the formatting): int((arctan(Pi*x)-arctan(x))/x, x = 0 .. infinity) In the problem statement it says you first need to express the integral as an iterated integral. I also know the answer is (π/2)ln(π).