Consider allnon empty subsets of the set .
For every subset we find the product of each of these elements.
Sum of all these products is?
Last edited by jacks (2012-12-10 07:59:38)
I am getting (n+1)! - 1 but I do not know of a proof of that.
In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.