Hi, am a bit stuck with this. Find the radius of convergence of the complex series (Sigma n=1 to infinity) (z - e)^n! I know that the answer is R=1 but I'm not sure how to get there. It's the factorial as a power which I'm not sure about, have seen this in some other problems too. I have tried using the Ratio Test to determine radius of convergence but doesn't seem to be working. Any ideas anyone? Thanks in advance, and apologies for the lack of Latex.