for , where is a Hypergeometric Function. If is a Negative Integer , this becomes

which is known as the Vandermonde Theorem.

**References**

Petkovsek, M.; Wilf, H. S.; and Zeilberger, D. *A=B.* Wellesley, MA: A. K. Peters, pp. 42 and 126, 1996.

© 1996-9

1999-05-25