Concrete Mathematics by Graham,Knuth, Patashnik is (explicitly, even) a mini-TAOCP for much* of the mathematical underpinnings of computer science.
* I say much rather than most or all since it's focused on asymptotics, recurrences, number theory. Modern theoretical Computer Science draws on a much wider variety of mathematical methods.
Concrete Mathematics is outstanding, and I'm happy to think I'm getting an overview of TAOCP by (very slowly) working my way through Concrete Mathematics.
* I say much rather than most or all since it's focused on asymptotics, recurrences, number theory. Modern theoretical Computer Science draws on a much wider variety of mathematical methods.