Mini Moose 2707 -- That's probably more concise. Depends where you want to do the heavy lifting of the proof.
Mini Moose 2707 -- n * (n+1) * (n+2). If n is even, then for some integer k you can write the original expression as (2k)(2k+1)(2k+2), obvious factor of 2 up front. If n is odd, then express it as (2k+1)(2k+2)(2k+3), factor a 2 from the middle term and put it up front.
Mini Moose 2707 -- Actually, you could probably do this whole thing quicker