2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/61268Consider the number of permutations in the symmetric group on n letters that contain c copies of a given pattern. As c varies (with n held fixed) these numbers form a sequence whose properties we study for the monotone patterns and the patterns 1, l, l-1, ..., 2. We show that, except for the patterns 1, 2 and 2, 1 where the sequence is well-known to be log concave, there are infinitely many n where the sequence has internal zeros.24 pagesCombinatorics05A05 (Primary) 05A20, 05E99, 06A07 (Secondary)text