Continued fractions and generalized patterns
Combinatorics
2007-05-23 v2
Abstract
In [BS] Babson and Steingrimsson introduced generalized permutation patterns that allow the requirement that two adjacent letters in a pattern must be adjacent in the permutation. Let be the number of -avoiding permutations on letters that contain exactly occurrences of , where a generalized pattern on letters. Let and be the generating functions defined by and . We find an explicit expression for in the form of a continued fraction for where given as a generalized pattern; , , , or . In particularly, we find for any generalized pattern of length 3. This allows us to express via Chebyshev polynomials of the second kind, and continued fractions.
Keywords
Cite
@article{arxiv.math/0110037,
title = {Continued fractions and generalized patterns},
author = {T. Mansour},
journal= {arXiv preprint arXiv:math/0110037},
year = {2007}
}
Comments
16 pages