Prove that the numbers that begin with 1 and end with 1, with any number of 2s in the middle, and all 1s and 2s separated by 00 are composite.

For example:
1002001
1002002001,
1002002002001,
1002002002002001

(In reply to Divisibility by Nick Hobson)

ooohhhh I'm in such a nitpicking mood today...

Similar to your "Formula None Racer" problem... I suggest that you demonstrate why the divisibility test, you refer to, works. Or at least provide a reference to it on the web (I saw plenty of those).

Posted by SilverKnight on 2003-10-10 16:33:58