A261663 Number of equivalence classes of permutations avoiding the pattern {123}.

1, 1, 2, 4, 8, 19, 41, 98, 221, 526

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: A139784 A247235 A369683 * A199694 A037444 A151526

Adjacent sequences: A261660 A261661 A261662 * A261664 A261665 A261666

Keyword

nonn,more

Author

N. J. A. Sloane, Aug 30 2015

Status

approved