Weakly Consecutive Sequences

Fuente: arXiv
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Main Authors: Garrison, Thomas, Seiler, Chris, Knowles, Andrew
Format: Preprint
Published: 2024
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author Garrison, Thomas
Seiler, Chris
Knowles, Andrew
author_facet Garrison, Thomas
Seiler, Chris
Knowles, Andrew
contents A weakly consecutive sequence (WCS) is a permutation $σ$ of $\{1, \ldots, k\}$ such that if an integer $d$ divides $σ(i)$, then $d$ also divides $σ(i \pm d)$ insofar as these are defined. The structure of weakly consecutive sequences is surprisingly rich, and it is difficult to find a formula for the number $N(k)$ of WCS's of length $k$. However, for a given $k$ we describe four starting sequences, to each of which we can apply three \emph{rules} or operations to generate new WCS's. We conjecture that any WCS can be constructed by applying these rules, which depend in an intricate way on the primality of $k$ and surrounding integers. We find bounds for $N(k)$ by analyzing these rules.
format Preprint
id arxiv_https___arxiv_org_abs_2401_09497
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Weakly Consecutive Sequences
Garrison, Thomas
Seiler, Chris
Knowles, Andrew
Combinatorics
A weakly consecutive sequence (WCS) is a permutation $σ$ of $\{1, \ldots, k\}$ such that if an integer $d$ divides $σ(i)$, then $d$ also divides $σ(i \pm d)$ insofar as these are defined. The structure of weakly consecutive sequences is surprisingly rich, and it is difficult to find a formula for the number $N(k)$ of WCS's of length $k$. However, for a given $k$ we describe four starting sequences, to each of which we can apply three \emph{rules} or operations to generate new WCS's. We conjecture that any WCS can be constructed by applying these rules, which depend in an intricate way on the primality of $k$ and surrounding integers. We find bounds for $N(k)$ by analyzing these rules.
title Weakly Consecutive Sequences
topic Combinatorics
url https://arxiv.org/abs/2401.09497