Restricted 132-Involutions
Séminaire lotharingien de combinatoire, Tome 48 (2002-2003)
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We study generating functions for the number of involutions of length n avoiding (or containing exactly once) 132 and avoiding (or containing exactly once) an arbitrary permutation \tau of length k. In several interesting cases these generating functions depend only on k and can be expressed via Chebyshev polynomials of the second kind. In particular, we show that involutions of length n avoiding both 132 and 12...k are equinumerous with involutions of length n avoiding both 132 and any extended double-wedge pattern of length k. We use combinatorial methods to prove several of our results.
@article{SLC_2002-2003_48_a0,
author = {Olivier Guibert and Toufik Mansour},
title = {Restricted {132-Involutions}},
journal = {S\'eminaire lotharingien de combinatoire},
publisher = {mathdoc},
volume = {48},
year = {2002-2003},
url = {http://geodesic.mathdoc.fr/item/SLC_2002-2003_48_a0/}
}
Olivier Guibert; Toufik Mansour. Restricted 132-Involutions. Séminaire lotharingien de combinatoire, Tome 48 (2002-2003). http://geodesic.mathdoc.fr/item/SLC_2002-2003_48_a0/