Math puzzle books

I read on Slate.com that Stephen Sondheim was so passionate about math as a young man that if he hadn’t found his way to the theater, he may have become a mathematician.

“Sondheim's tricky, compact, dense lyrics work almost like puzzles (he is a big cryptic crossword fan), and draw from his earliest instincts about music and art. He was a math student at college and only took a course in music because the tutor promised to strip it of romanticism and approach it, said Sondheim, as a ‘mathematical art’. The geometry of things, how they connect and draw attention to their own composition, is a presiding interest, as is technical precision…” — From The Guardian.