2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/66009In this paper we prove that among the permutations of length n with i fixed points and j excedances, the number of 321-avoiding ones equals the number of 132-avoiding ones, for all given i,j<=n. We use a new technique involving diagonals of non-rational generating functions. This theorem generalizes a recent result of Robertson, Saracino and Zeilberger, for which we also give another, more direct proof.12 pages, 10 figures, submitted to FPSAC'03Combinatorics05A15text