Restricted 132-Dumont permutations
Abstract
A permutation is said to be {\em Dumont permutations of the first kind} if each even integer in must be followed by a smaller integer, and each odd integer is either followed by a larger integer or is the last element of (see, for example, \cite{Z}). In \cite{D} Dumont showed that certain classes of permutations on letters are counted by the Genocchi numbers. In particular, Dumont showed that the st Genocchi number is the number of Dummont permutations of the first kind on letters. In this paper we study the number of Dumont permutations of the first kind on letters avoiding the pattern 132 and avoiding (or containing exactly once) an arbitrary pattern on letters. In several interesting cases the generating function depends only on .
Cite
@article{arxiv.math/0209379,
title = {Restricted 132-Dumont permutations},
author = {T. Mansour},
journal= {arXiv preprint arXiv:math/0209379},
year = {2007}
}
Comments
12 pages