A217803 - OEIS

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A217803

Number of alternating permutations on 2n+1 letters that avoid a certain pattern of length 4 (see Lewis, 2012, Appendix, for precise definition).

0

1, 2, 12, 108, 1202, 15234, 210696, 3102296, 47875884

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OFFSET

0,2

LINKS

Table of n, a(n) for n=0..8.

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: A265132 A080446 A301411 * A177409 A360950 A212273

Adjacent sequences: A217800 A217801 A217802 * A217804 A217805 A217806

KEYWORD

nonn,more

AUTHOR

N. J. A. Sloane, Oct 12 2012

EXTENSIONS

a(6)-a(8) from Lars Blomberg, Jan 23 2018

STATUS

approved