>>> def crible(prems):
...     if prems == []: return []
...     return [prems[0]] + crible([p for p in prems[1:] if p % prems[0] != 0])
...
>>> crible(range(2, 100))
[2, 3, 5, 7, 11, 13, 17, 19, 23, 29, 31, 37, 41, 43, 47, 53, 59, 61, 67, 71, 73, 79, 83, 89, 97]