[Jtsummers]

Seconding this book. I jumped back to the beginning of his recreational logic books and have been reading through them this year. Lots of fun, and as a programmer there’s an extra (self-induced) challenge to explore programs that can generate, solve, or interpret the systems and problems he sets up.

[a4isms]

Thirding.

[vga805]

Fourthing.

And also his Godelian Puzzle Book, much fun!