A116843 - OEIS

A116843

Number of permutations of length n which avoid the patterns 1342, 3241, 4312.

1, 2, 6, 21, 73, 241, 759, 2305, 6806, 19652, 55725, 155688, 429719, 1174344, 3183298, 8571979, 22958381, 61220351, 162668347, 430978487, 1139179386, 3005433282, 7916965441, 20829348046, 54747238203, 143781463846

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OFFSET

1,2

LINKS

Table of n, a(n) for n=1..26.

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 96.

Lara Pudwell, Systematic Studies in Pattern Avoidance, 2005.

Index entries for linear recurrences with constant coefficients, signature (11,-51,130,-199,187,-105,32,-4).

FORMULA

G.f.: A(x) = -{(8x^7-26x^6+60x^5-87x^4+73x^3-35x^2+9x-1)x}/{(2x-1)^2(x-1)^4(x^2-3x+1)}

CROSSREFS

Sequence in context: A294803 A116773 A116741 * A116822 A116797 A294804

Adjacent sequences: A116840 A116841 A116842 * A116844 A116845 A116846

KEYWORD

nonn,easy

AUTHOR

Lara Pudwell, Feb 26 2006

STATUS

approved