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A116763
Number of permutations of length n which avoid the patterns 2134, 3241, 3421.
0
1, 2, 6, 21, 75, 255, 813, 2443, 6985, 19175, 50917, 131555, 332257, 823263, 2007005, 4825051, 11460569, 26935255, 62717909, 144834515, 332005329, 756023247, 1711275981, 3852468171, 8629780425, 19243466695, 42731569093, 94522834883
OFFSET
1,2
LINKS
FORMULA
G.f.: A(x) = {x(2x^6-18x^5+39x^4-45x^3+27x^2-8x+1)}/{(x-1)^2(2x-1)^4}
CROSSREFS
Sequence in context: A150187 A116818 A294770 * A116840 A116841 A116814
KEYWORD
nonn,easy
AUTHOR
Lara Pudwell, Feb 26 2006
STATUS
approved