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.
No great discovery was ever made without a bold guess.