Inversion sequences avoiding 021 and another pattern of length four

Toufik Mansour, Gökhan Yıldırım

Research output: Contribution to journalArticlepeer-review


We study the enumeration of inversion sequences that avoid pattern 021 and another pattern of length four. We determine the generating trees for all possible pattern pairs and compute the corresponding generating functions. We introduce the concept of d-regular generating trees and conjecture that for any 021-avoiding pattern τ, the generating tree T ({021, τ}) is d-regular for some integer d.

Original languageEnglish
Pages (from-to)1-23
Number of pages23
JournalDiscrete Mathematics and Theoretical Computer Science
StatePublished - 2023

Bibliographical note

Publisher Copyright:
© 2023 by the author(s)


  • Catalan numbers
  • Motzkin numbers
  • Pattern-avoiding inversion sequences
  • generating functions
  • generating trees
  • kernel method

ASJC Scopus subject areas

  • Theoretical Computer Science
  • General Computer Science
  • Discrete Mathematics and Combinatorics


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