No,i meant sum of digits is prime and also sum of square of digits is prime. E.g: 23 is lucky cos 2+3=>5 (prime) 2**2+3**2 => 4+9 => 13 (prime) -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://mail.python.org/pipermail/tutor/attachments/20120124/d300442e/attachment.html>