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A261664 Number of equivalence classes of permutations avoiding the pattern {231}. 0
1, 1, 2, 4, 9, 21, 50, 121, 296, 729 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,3

COMMENTS

It seems that there is no known g.f.

LINKS

Table of n, a(n) for n=0..9.

J.-L. Baril, T. Mansour, A. Petrossian, Equivalence classes of permutations modulo excedances, Journal of Combinatorics, Volume 5 (2014), Number 4, doi:10.4310/JOC.2014.v5.n4.a4.

CROSSREFS

Sequence in context: A171842 A296201 A027826 * A091964 A092423 A238438

Adjacent sequences:  A261661 A261662 A261663 * A261665 A261666 A261667

KEYWORD

nonn,more

AUTHOR

N. J. A. Sloane, Aug 30 2015

STATUS

approved

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Last modified March 24 19:48 EDT 2019. Contains 321448 sequences. (Running on oeis4.)