A Combinatorial Interpretation for Sequence A345973 in OEIS

2021/08/10 by David Callan, Callan, David
Computer Science · Mathematics · #05A15 #Advanced Combinatorial Mathematics #Combinatorics (math.CO) #FOS: Mathematics #semigroups and automata theory

paper · pdf · doi:10.48550/arxiv.2108.04969

openalex publication_date 2021/08/10 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28

Abstract

We give a combinatorial interpretation in terms of bicolored ordered trees for the sequence (a_n)_n>=1=(1, 1, 1, 2, 3, 6, 10, 20, 36, 73,... ), A345973 in OEIS, whose generating function satisfies the defining identity Sum_n>=1a_n xⁿ = x + x²/Product_n>=1(1 - a_n xⁿ).

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