First of all, there are plenty of people who solved both large inputs with Python/Ruby (with and without pre-computing all the fair and square numbers).[0][1]

As others have stated, the contests are designed such that language shouldn't matter and problem sets are deemed solvable with Python as a baseline. For this particular question, the official contest analysis goes into detail on how to reduce the solution space:

https://code.google.com/codejam/contest/2270488/dashboard#s=...

Now the issue becomes the trade off between development speed vs runtime performance.

Is it possible that you might solve the problem with a worse solution in a better performing language? Yes.

Is it possible you might finish a solution within the time constraints in a more expressive language? Yes.

If something is CPU bound in production, then going with a better performing language is a viable consideration.[2] However, my goal in programming contests is often to become a better programmer in the process. As a result, I choose to focus more on improving algorithmic complexity which is language agnostic.

[0]: http://www.go-hero.net/jam/13/solutions/0/3/Ruby

[1]: http://www.go-hero.net/jam/13/solutions/0/3/Python

[2]: For the pedantic, I understand that language performance is different from implementation performance.

Edit: Corrected links, thanks victorhn.