Partial Deranged Bell Numbers and Their Combinatorial Properties

Fuente: arXiv
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Main Authors: Djemmada, Yahia, Kargın, Levent, Can, Mümün
Format: Preprint
Published: 2025
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author Djemmada, Yahia
Kargın, Levent
Can, Mümün
author_facet Djemmada, Yahia
Kargın, Levent
Can, Mümün
contents We introduce a novel generalization of deranged Bell numbers by defining the partial deranged Bell numbers $w_{n,r}$, which count the number of set partitions of $\left[ n\right] $ with exactly $r$ fixed blocks, while the remaining blocks are deranged. This construction provides a unified framework that connects partial derangements, Stirling numbers, and ordered Bell numbers. We investigate their combinatorial properties, including explicit formulas, generating functions, and recurrence relations. Moreover, we demonstrate that these numbers are expressible in terms of classical sequences such as deranged Bell numbers and ordered Bell numbers, and reveal their relationship to complementary Bell numbers, offering insights relevant to Wilf's conjecture. Notably, we derive the identity \[ \tildeϕ_{n}=\Tilde{w}_{n,0}-\Tilde{w}_{n,1}=\tilde{w}_{n-1,0}-2\tilde {w}_{n-1,2}, \] which illustrates their structural connection to complementary Bell numbers. We also introduce a polynomial expansion for these numbers and explore their connections with exponential polynomials, geometric polynomials, and Bernoulli numbers. These relationships facilitate the derivation of closed-form expressions for certain finite summations involving Stirling numbers of the second kind, Bernoulli numbers, and binomial coefficients, articulated through partial derangement numbers.
format Preprint
id arxiv_https___arxiv_org_abs_2507_21643
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Partial Deranged Bell Numbers and Their Combinatorial Properties
Djemmada, Yahia
Kargın, Levent
Can, Mümün
Combinatorics
05A18, 05A19, 11B73, 11B75, 11B68
We introduce a novel generalization of deranged Bell numbers by defining the partial deranged Bell numbers $w_{n,r}$, which count the number of set partitions of $\left[ n\right] $ with exactly $r$ fixed blocks, while the remaining blocks are deranged. This construction provides a unified framework that connects partial derangements, Stirling numbers, and ordered Bell numbers. We investigate their combinatorial properties, including explicit formulas, generating functions, and recurrence relations. Moreover, we demonstrate that these numbers are expressible in terms of classical sequences such as deranged Bell numbers and ordered Bell numbers, and reveal their relationship to complementary Bell numbers, offering insights relevant to Wilf's conjecture. Notably, we derive the identity \[ \tildeϕ_{n}=\Tilde{w}_{n,0}-\Tilde{w}_{n,1}=\tilde{w}_{n-1,0}-2\tilde {w}_{n-1,2}, \] which illustrates their structural connection to complementary Bell numbers. We also introduce a polynomial expansion for these numbers and explore their connections with exponential polynomials, geometric polynomials, and Bernoulli numbers. These relationships facilitate the derivation of closed-form expressions for certain finite summations involving Stirling numbers of the second kind, Bernoulli numbers, and binomial coefficients, articulated through partial derangement numbers.
title Partial Deranged Bell Numbers and Their Combinatorial Properties
topic Combinatorics
05A18, 05A19, 11B73, 11B75, 11B68
url https://arxiv.org/abs/2507.21643