"Project Euler is a series of challenging mathematical/computer programming problems that will require more than just mathematical insights to solve. Although mathematics will help you arrive at elegant and efficient methods, the use of a computer and programming skills will be required to solve most problems."The project was started in 2001 and now has 230 problems. Each one has a short description and can be solved by a computer program that runs in a minute or less on a modest computer. Here's an example of one of the problems (#5):
"2520 is the smallest number that can be divided by each of the numbers from 1 to 10 without any remainder.What is the smallest number that is evenly divisible by all of the numbers from 1 to 20?"The site shows statistics (if you register) that show the programming languages used by people who have submitted solutions. Python is second only to C/C++ in the ranking.