A217817 Number of alternating permutations on 2n letters that avoid a certain pattern of length 5 (see Lewis, 2012, Appendix, for precise definition).

1, 5, 56, 997, 23653, 679810, 22394962, 816872290

Offset: 1

Author

N. J. A. Sloane, Oct 13 2012

Keywords

• nonn
• more

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.

Extensions

a(7)-a(8) from Lars Blomberg, Feb 28 2018