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Some determinantal representations of derangement numbers and polynomials

  • Chak-On Chow

摘要

Munarini (J Integer Seq 23: Article 20.3.8, 2020) recently showed that the derangement polynomial \(d_n(q)=\sum _{\sigma \in {\mathcal {D}}_n}q^{{{\,\textrm{maj}\,}}(\sigma )}\) d n ( q ) = σ D n q maj ( σ ) is expressible as the determinant of either an \(n\times n\) n × n tridiagonal matrix or an \(n\times n\) n × n lower Hessenberg matrix. Qi et al. (Cogent Math 3:1232878, 2016) showed that the classical derangement number \(d_n=n!\sum _{k=0}^n\frac{(-1)^k}{k!}\) d n = n ! k = 0 n ( - 1 ) k k ! is expressible as a tridiagonal determinant of order \(n+1\) n + 1 . We show in this work that similar determinantal expressions exist for the type B derangement polynomial \(d_n^B(q)=\sum _{\sigma \in {\mathcal {D}}_n^B}q^{{{\,\textrm{fmaj}\,}}(\sigma )}\) d n B ( q ) = σ D n B q fmaj ( σ ) studied previously by Chow (Sém Lothar Combin 55:B55b, 2006), and the type D derangement polynomial \(d_n^D(q)=\sum _{\sigma \in {\mathcal {D}}_n^D}q^{{{\,\textrm{maj}\,}}(\sigma )}\) d n D ( q ) = σ D n D q maj ( σ ) studied recently by Chow (Taiwanese J Math 27(4):629–646, 2023). Representations of the types B and D derangement numbers \(d_n^B\) d n B and \(d_n^D\) d n D as determinants of order \(n+1\) n + 1 are also presented.