A217823 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, 1, 9, 153, 3579, 101630, 3288871

Offset: 0

Author

N. J. A. Sloane, Oct 13 2012

Keywords

• nonn
• more

Comments

Is this the same sequence as A361190?

Links

• 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, A361190.

Extensions

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

a(0)=1 prepended by Alois P. Heinz, Jul 31 2023