Pattern-Avoidance and Fuss-Catalan Numbers
Per Alexandersson
Department of Mathematics
Stockholm University
S-106 91 Stockholm
Sweden
Frether Getachew Kebede
Department of Mathematics
Addis Ababa University
1176 Addis Ababa
Ethiopia
Samuel Asefa Fufa
Department of Mathematics
Addis Ababa University
1176 Addis Ababa
Ethiopia
Dun Qiu
Center for Combinatorics, LPMC
Nankai University
Tianjin 300071
P. R. China
Abstract:
We study a subset of permutations where entries are restricted to having
the same remainder as the index, modulo some integer k ≥ 2. We show
that by also imposing the classical 132- or 213-avoidance restriction on
the permutations, we recover the Fuss–Catalan numbers and some special
cases of the Raney numbers. Surprisingly, an analogous statement also
holds when we impose the mod k restriction on a Catalan family of
subexcedant functions. Finally, we completely enumerate all combinations
of mod-k-alternating permutations that avoid two patterns of length
3. This is analogous to the systematic study by Simion and Schmidt,
of permutations avoiding two patterns of length 3.
Full version: pdf,
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(Concerned with sequences
A000027
A000045
A000079
A000124
A047749
A079508
A335109
A354208
A355089
A355262.)
Received May 24 2022; revised versions received January 23 2023; January 24 2023; February
25 2023; April 6 2023.
Published in Journal of Integer Sequences,
April 7 2023.
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