I found my Riemann Zeta book Friday night. I say 'found' because after a few weeks of tripping on the Zeta, I try to 'hide' this book so that I forget about Zeta for a little bit.
Now I've been summing up series like crazy for a day or two. A recurring these in my own little math sessions is the hyperbolic(not in sense of 'hyperbola') use of infinite series and orthogonal function expansions.
Now I want Hardy's Divergent Series book!