"Concrete Mathematics" by Graham, Knuth and Patashnik is probably the best preparation for tackling TAoCP, though it is not light reading either. You could als

"Concrete Mathematics" by Graham, Knuth and Patashnik is probably the best preparation for tackling TAoCP, though it is not light reading either. You could also look at "Mathematics for Computer Science" by Lehman, Leighton, and Meyer. It is available at http://courses.csail.mit.edu/6.042/fall10/mcs-ftl.pdf http://courses.csail.mit.edu/6.042/fall10/mcs-ftl.pdf .