English

Permutations with a fixed number of occurrences of a monotone pattern

Combinatorics 2025-10-29 v2

Abstract

We bound the number of permutations with a fixed number rr of 321p0321 \ominus p_0 patterns by a constant times the number of permutations which avoid 321p0321 \ominus p_0. We use this new upper bound to show that the ordinary generating function for permutations with rr copies of k(k1)...1k(k-1)...1 is not rational for odd k3k \geq 3 and not algebraic for even k3k \geq 3.

Keywords

Cite

@article{arxiv.2506.05712,
  title  = {Permutations with a fixed number of occurrences of a monotone pattern},
  author = {Michael Waite},
  journal= {arXiv preprint arXiv:2506.05712},
  year   = {2025}
}

Comments

13 pages, 8 figures, Revision: new results and changed title