A nice identity
Source: Romania TST 1991
November 8, 2009
inductionLaTeXlogarithmscombinatorics unsolvedcombinatorics
Problem Statement
Prove the following identity for every :
\sum_{j\plus{}h\equal{}n,j\geq h}\frac{(\minus{}1)^h2^{j\minus{}h}\binom{j}{h}}{j}\equal{}\frac{2}{n}