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arXiv · 2506.05712

Permutations with a fixed number of occurrences of a monotone pattern

Michael Waite
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Abstract

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

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Michael Waite. 2025-10-28. Permutations with a fixed number of occurrences of a monotone pattern. https://arxiv.org/abs/2506.05712

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