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A116843
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Number of permutations of length n which avoid the patterns 1342, 3241, 4312.
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0
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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
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1,2
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LINKS
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FORMULA
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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)}
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CROSSREFS
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KEYWORD
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nonn,easy
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AUTHOR
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STATUS
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approved
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