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A116740
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Number of permutations of length n which avoid the patterns 1243, 2341, 4132.
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0
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1, 2, 6, 21, 73, 239, 740, 2199, 6348, 17947, 49954, 137372, 374164, 1011303, 2716439, 7259970, 19324340, 51268390, 135658217, 358193704, 944162051, 2485297822, 6534794291, 17167312441, 45067797703, 118245785494
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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) = -{(6x^8-36x^7+91x^6-149x^5+160x^4-108x^3+44x^2-10x+1)x}/{(2x-1)^2(x-1)^5(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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