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A324133 Number of permutations of [n] that avoid the shuffle pattern s-k-t, where s = 12 and t = 12. 0
1, 1, 2, 6, 24, 114, 608, 3554, 22480, 152546, 1103200, 8456994, 68411632, 581745250, 5183126016, 48245682338, 467988498064, 4720072211938, 49400302118560, 535546012710434, 6004045485933104, 69507152958422370, 829789019700511040, 10202854323325253538, 129061753086335478736 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,3

LINKS

Table of n, a(n) for n=0..24.

Sergey Kitaev, Partially Ordered Generalized Patterns, Discrete Math. 298 (2005), no. 1-3, 212-229.

FORMULA

a(n) = -2^(n-1) + 2*Sum_{i = 0..n-1} binomial(n-1,i) * a(i) with a(0) = 1. [It follows from Kitaev's recurrence for C_n on p. 220 of his paper.] - Petros Hadjicostas, Oct 30 2019

CROSSREFS

Cf. A000142.

Sequence in context: A209625 A054872 A134664 * A171448 A068199 A189846

Adjacent sequences:  A324130 A324131 A324132 * A324134 A324135 A324136

KEYWORD

nonn,changed

AUTHOR

N. J. A. Sloane, Feb 16 2019

EXTENSIONS

More terms from Petros Hadjicostas, Oct 30 2019

STATUS

approved

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Last modified November 13 00:25 EST 2019. Contains 329083 sequences. (Running on oeis4.)