I really like "Concrete Mathematics". It has nice, interesting problems, a very readable style, and introduces all notation used. It also has well written sol

I really like "Concrete Mathematics". It has nice, interesting problems, a very readable style, and introduces all notation used. It also has well written solutions to all of the problems. That said, I read the book after I had a math degree, so while it seems very accessible (more so than most undergrad discrete math books), perhaps someone who read it as an undergrad can comment.