38th Austrian Mathematical Competition 2007
Source: round2 problem3 - product of the elements of subsets
February 7, 2009
inductioncombinatorics unsolvedcombinatorics
Problem Statement
Let M(n )\equal{}\{\minus{}1,\minus{}2,\ldots,\minus{}n\}. For every non-empty subset of we consider the product of its elements. How big is the sum over all these products?