from util import primefactors print max(primefactors(600851475143))
from itertools import count from util import primefactors #jumping ahead for convenience #you must of course verify 0-start aren't #solutions start = 134000 num = 0 for i in count(start): if len(primefactors(i)) == 4: num += 1 if num == 4: print i - 3 break else: num = 0