It's a collection of math (often number theory) problems that programming can be used to solve. The first 50 are mostly reasonable, and many of them are trivial. Many of them build on previous, so you should start with the lower numbers.
Due to the reasons discussed here
we will be moving to python-forum.io
on October 1, 2016.
This forum will be locked down and no one will be able to post/edit/create threads, etc. here from thereafter. Please create an account at the new site to continue discussion.