I've been on the lookout for a way to maintain my coding skills and simultaneously apply my maths knowledge. I'm glad to have found it:

projecteuler.net

Project Euler provides mathematical problems that require a computer and programming to be solved. For example, in order to even register for the site, one must solve the following problem:

A number is a perfect square, or a square number, if it is the square of a positive integer.

For example, 25 is a square number because 5^2=5 \times 5=25; it is also an odd square.

The first 5 square numbers are: 1,4,9,16,25, and the sum of the odd squares is 1+9+25=35.

Among the first 290 thousand square numbers, what is the sum of all the odd squares?

I won't give away the answer, in accordance with the Project Euler code of conduct. In fact, on Project Euler's registration page, you'll find an appropriate quote by Plato:

Let none but enquiring minds enter.