A217808 Number of alternating permutations on 2n letters that avoid a certain pattern of length 4 (see Lewis, 2012, Appendix, for precise definition).

1, 5, 42, 453, 5651, 77498, 1135828, 17485309, 279540684

Offset

1,2

Links

Table of n, a(n) for n=1..9.

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: A327272 A024492 A217805 * A217810 A151334 A005789

Adjacent sequences: A217805 A217806 A217807 * A217809 A217810 A217811

Keyword

nonn,more

Author

N. J. A. Sloane, Oct 12 2012

Extensions

a(7)-a(9) from Lars Blomberg, Feb 17 2018

Status

approved