I agree they aren't complex, but he has yet to even learn functions according to his first post. So it still might be a tad premature (although length wise the code would be about the same).
@Mek - sieves aren't very complicated at all. In fact, they're pretty trivial in python, and worth exploring.
Anyway, I would love to see a sieve discussion start as I was just trying to optimize mine yesterday and it still seems a bit... lacking. I haven't gotten around to doing any other than Eratosthenes thus far though.