Simple quadratic sieve algo

Written just for educational purposes. If you need performance, choose anything else. This version is written to understand how it works.

You have to tune primes and sieving_array_size before lauching.

Using of pypy interpreter is strongly recomended.

Timing on pypy

Answer: 1819935140393 and 1001338283189

real 0m10.255s user 0m10.154s sys 0m0.082s