English

Alternating runs of permutations and the central factorial numbers

Combinatorics 2022-03-07 v3

Abstract

Let R(n,k) be the number of permutations of {1,2,,n}\{1,2,\ldots,n\} with k alternating runs. In this paper, we establish the relationships between R(n,k) and the central factorial numbers of even indices as well as the number of signed permutations with a given number of alternating runs and the central factorial numbers of odd indices. The explicit formulas of the peak and left peak polynomials for permutations and the derivative polynomials of the tangent and secant functions are also established.

Keywords

Cite

@article{arxiv.2202.13978,
  title  = {Alternating runs of permutations and the central factorial numbers},
  author = {Qi Fang and Ya-Nan Feng and Shi-Mei Ma},
  journal= {arXiv preprint arXiv:2202.13978},
  year   = {2022}
}

Comments

10 pages