132-avoiding Two-stack Sortable Permutations, Fibonacci Numbers, and Pell Numbers
| dc.creator | Egge, Eric S. | |
| dc.creator | Mansour, Toufik | |
| dc.date | 2002-05-19 | |
| dc.date.accessioned | 2026-07-07T04:48:35Z | |
| dc.date.available | 2026-07-07T04:48:35Z | |
| dc.description | In 1990 West conjectured that there are $2(3n)!/((n+1)!(2n+1)!)$ two-stack sortable permutations on $n$ letters. This conjecture was proved analytically by Zeilberger in 1992. Later, Dulucq, Gire, and Guibert gave a combinatorial proof of this conjecture. In the present paper we study generating functions for the number of two-stack sortable permutations on $n$ letters avoiding (or containing exactly once) 132 and avoiding (or containing exactly once) an arbitrary permutation $τ$ on $k$ letters. In several interesting cases this generating function can be expressed in terms of the generating function for the Fibonacci numbers or the generating function for the Pell numbers. | |
| dc.description | 17 pages | |
| dc.identifier | https://arxiv.org/abs/math/0205206 | |
| dc.identifier | http://arxiv.org/abs/math/0205206 | |
| dc.identifier.uri | http://salesiana.dossiersoluciones.com/handle/123456789/64105 | |
| dc.subject | Combinatorics | |
| dc.subject | 05A15 | |
| dc.title | 132-avoiding Two-stack Sortable Permutations, Fibonacci Numbers, and Pell Numbers | |
| dc.type | text |