Project Euler has been around for a really long time, comprising, at the time of writing, 882 problems (!). They are mathematical in nature (at least so far!), and easily translate to computer programming problems.

I use these problems to practice my Scheme programming, but they usually help in brushing my mathematics too. And every problem has an associated guided solution, which is a tremendous resource to explore other avenues of solving a given problem.

My solutions are here, and I'll update as these are done.