Permutations avoiding a nonconsecutive instance of a 2- or 3-letter pattern
组合数学
2007-05-23 v2
摘要
We count permutations avoiding a nonconsecutive instance of a two- or three-letter pattern, that is, the pattern may occur but only as consecutive entries in the permutation. Two-letter patterns give rise to the Fibonacci numbers. The counting sequences for the two representative three-letter patterns, 321 and 132, have respective generating functions (1+x^2)(C(x)-1)/(1+x+x^2-x C(x)) and C(x+x^3) where C(x) is the generating function for the Catalan numbers.
引用
@article{arxiv.math/0610428,
title = {Permutations avoiding a nonconsecutive instance of a 2- or 3-letter pattern},
author = {David Callan},
journal= {arXiv preprint arXiv:math/0610428},
year = {2007}
}
备注
Acknowledgment of priority