English

Generalized Eulerian Numbers

Combinatorics 2023-06-22 v1

Abstract

Let A(n,m)A(n,m) denote the Eulerian numbers, which count the number of permutations on [n][n] with exactly mm descents. It is well known that A(n,m)A(n,m) also counts the number of permutations on [n][n] with exactly mm excedances. In this report, we define numbers of the form A(n,m,k)A(n,m,k), which count the number of permutations on [n][n] with exactly mm descents and the last element kk. We then show bijections between this definition and various other analogs for rr-excedances and rr-descents. We also prove a variation of Worpitzky's identity on A(n,m,k)A(n,m,k) using a combinatorial argument mentioned in a paper by Spivey in 2021.

Keywords

Cite

@article{arxiv.2306.11836,
  title  = {Generalized Eulerian Numbers},
  author = {David Dong},
  journal= {arXiv preprint arXiv:2306.11836},
  year   = {2023}
}

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15 pages, 0 figures