$q$-Super Catalan Numbers: Combinatorial identities, Generating Functions, and Narayana Refinements

Fuente: arXiv
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Main Authors: Rodelet--Causse, Arthur, Tevlin, Lenny
Format: Preprint
Published: 2025
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author Rodelet--Causse, Arthur
Tevlin, Lenny
author_facet Rodelet--Causse, Arthur
Tevlin, Lenny
contents We begin by deriving a number of combinatorial identities satisfied by the $q$-super Catalan numbers. In particular, we extend some of the known combinatorial identities (Touchard, Koshy, Reed Dawson) to the $q$-super Catalan numbers. Next, we introduce some $q$-convolution identities involving q-central binomial and q-Catalan numbers and derive a generating function for $q$-Catalan numbers. Then we introduce Narayana-type refinements of the super Catalan numbers. We prove algebraically the $γ$-positivity of those refinements and give a combinatorial proof in a special case through the type B analog of noncrossing partitions. Then we introduce their natural $q$-analogs, prove their $q$-$γ$-positivity and prove some identities they satisfy, generalizing identities of Kreweras and Le Jen-Shoo. Using yet another identity, we prove that these refinements are positive integer polynomials in $q$.
format Preprint
id arxiv_https___arxiv_org_abs_2505_09821
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle $q$-Super Catalan Numbers: Combinatorial identities, Generating Functions, and Narayana Refinements
Rodelet--Causse, Arthur
Tevlin, Lenny
Combinatorics
Number Theory
05A10, 11B65
We begin by deriving a number of combinatorial identities satisfied by the $q$-super Catalan numbers. In particular, we extend some of the known combinatorial identities (Touchard, Koshy, Reed Dawson) to the $q$-super Catalan numbers. Next, we introduce some $q$-convolution identities involving q-central binomial and q-Catalan numbers and derive a generating function for $q$-Catalan numbers. Then we introduce Narayana-type refinements of the super Catalan numbers. We prove algebraically the $γ$-positivity of those refinements and give a combinatorial proof in a special case through the type B analog of noncrossing partitions. Then we introduce their natural $q$-analogs, prove their $q$-$γ$-positivity and prove some identities they satisfy, generalizing identities of Kreweras and Le Jen-Shoo. Using yet another identity, we prove that these refinements are positive integer polynomials in $q$.
title $q$-Super Catalan Numbers: Combinatorial identities, Generating Functions, and Narayana Refinements
topic Combinatorics
Number Theory
05A10, 11B65
url https://arxiv.org/abs/2505.09821