Permutations with a fixed number of occurrences of a pattern: A case generalizing 231

Abstract

We determine a set of permutation patterns $q$ so that the number of permutations with $r$ occurrences of $q$ is asymptotically $n^r$ times the number of permutations avoiding $q$, partially settling a conjecture of Conway and Guttman. We also use these asymptotics to prove nonrationality and nonalgebraicity for certain ordinary generating functions for permutations with $r$ copies of a pattern.

arXiv comment10 pages, 2 figures, Revision: fixed some typos and small errors