A217822 Number of permutations of length 3n with descent set {3, 6, ...} that avoid a certain pattern of length 4 or 5 (see Lewis, 2012, Appendix, for precise definition).

1, 9, 153, 3465, 92169, 2716425

Offset

1,2

Links

Table of n, a(n) for n=1..6.

J. B. Lewis, Pattern Avoidance for Alternating Permutations and Reading Words of Tableaux, Ph. D. Dissertation, Department of Mathematics, MIT, 2012.

Crossrefs

Cf. A181197, A217799-A217830.

Sequence in context: A133309 A228713 A151835 * A217823 A361190 A113391

Adjacent sequences: A217819 A217820 A217821 * A217823 A217824 A217825

Keyword

nonn,more

Author

N. J. A. Sloane, Oct 13 2012

Extensions

a(5)-a(6) from Lars Blomberg, Mar 09 2018

Status

approved