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Combinatorial proofs of inverse relations and log-concavity for Bessel numbers

Hyuk Han·Seunghyun Seo
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Abstract

Let the Bessel number of the second kind B(n,k) be the number of set partitions of [n] into k blocks of size one or two, and let the Bessel number of the first kind b(n,k) be a certain coefficient in n-th Bessel polynomial. In this paper, we show that Bessel numbers satisfy two properties of Stirling numbers: The two kinds of Bessel numbers are related by inverse formulas, and both Bessel numbers of the first kind and the second kind form log-concave sequences. By constructing sign-reversing involutions, we prove the inverse formulas. We review Krattenthaler's injection for the log-concavity of Bessel numbers of the second kind, and give a new explicit injection for the log-concavity of signless Bessel numbers of the first kind.

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Hyuk Han, Seunghyun Seo. 2004-06-20. Combinatorial proofs of inverse relations and log-concavity for Bessel numbers. https://arxiv.org/abs/math/0406378

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