Izzy, Not to critique your notation, but what does "E O" mean? Thanks. Ben

> Date: Sat, 16 Oct 2010 22:10:11 -0400 > From: discussions@mathforum.org > To: discretemath@mathforum.org > Subject: need help with a question > > Prove that a! E O(aa) > > p.s (aa) is suppose to be "a to the power of a"