The number of \bar{2}413\bar{5}-avoiding permutations
Combinatorics
2011-11-03 v3
Abstract
We answer a question of R. J. Mathar and confirm that the counting sequence for -avoiding permutations is the Invert transform of the Bell numbers. The proof relies on a simple decomposition of these permutations and the known fact that -avoiding permutations are counted by the Bell numbers.
Keywords
Cite
@article{arxiv.1110.6884,
title = {The number of \bar{2}413\bar{5}-avoiding permutations},
author = {David Callan},
journal= {arXiv preprint arXiv:1110.6884},
year = {2011}
}
Comments
4 pages, typos corrected, slightly improved exposition