Short Proofs of Combinatorial Identities For n!

Angel Plaza1, Sergio Falcon2
1DEPARTMENT OF MATHEMATICS, UNIV. LAS PALMAS DE GRAN CANARIA, 35017-LaAS PatMas G.C., SPAIN
2DEPARTMENT OF MATHEMATICS, Untv. LAS PALMAS DE GRAN CANARIA, 35017-Las PaLmas G.C., SPAIN