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A116781 Number of permutations of length n which avoid the patterns 1234, 1243, 3214. 0
1, 2, 6, 21, 73, 250, 861, 2967, 10220, 35203, 121263, 417710, 1438865, 4956391, 17073052, 58810751, 202582667, 697827126, 2403772765, 8280164651, 28522299468, 98249443251, 338435304271, 1165792409470, 4015751089881 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

LINKS

Table of n, a(n) for n=1..25.

D. Callan, T. Mansour, Enumeration of small Wilf classes avoiding 1324 and two other 4-letter patterns, arXiv:1705.00933 [math.CO] (2017), Table 2 No 113.

Lara Pudwell, Systematic Studies in Pattern Avoidance, 2005.

Index entries for linear recurrences with constant coefficients, signature (3,1,2,0,-2)

FORMULA

G.f.: A(x) = -{x(x^3+x^2+x-1)}/{2x^5-2x^3-x^2-3x+1}

CROSSREFS

Sequence in context: A116828 A294764 A116837 * A047106 A148487 A148488

Adjacent sequences:  A116778 A116779 A116780 * A116782 A116783 A116784

KEYWORD

nonn,easy

AUTHOR

Lara Pudwell, Feb 26 2006

STATUS

approved

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Last modified June 25 03:46 EDT 2022. Contains 354835 sequences. (Running on oeis4.)