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A136592
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Column 2 of triangle A136590.
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4
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1, 3, -13, -10, 394, -2016, -5076, 170064, -1155024, -5005440, 193724640, -1656720000, -10280355840, 465087087360, -4804977542400, -39012996556800, 2035558551398400, -24660231399014400, -248246498826547200, 14713557956794368000
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OFFSET
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2,2
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LINKS
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Table of n, a(n) for n=2..21.
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FORMULA
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E.g.f.: A(x) = log(1 + x + x^2)^2 / 2!.
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EXAMPLE
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E.g.f.: A(x) = 1*x^2/2! + 3*x^3/3! - 13*x^4/4! - 10*x^5/5! + 394*x^6/6! +...
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MATHEMATICA
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With[{nn=30}, Drop[CoefficientList[Series[Log[1+x+x^2]^2/2, {x, 0, nn}], x] Range[ 0, nn]!, 2]] (* Harvey P. Dale, Feb 28 2013 *)
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PROG
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(PARI) a(n)=(n+2)!*polcoeff(log(1+x+x^2 +x*O(x^(n+2)))^2/2!, n+2)
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CROSSREFS
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Cf. A136590, A136591, A136593, A136594.
Sequence in context: A273025 A273122 A071708 * A085416 A107802 A142351
Adjacent sequences: A136589 A136590 A136591 * A136593 A136594 A136595
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KEYWORD
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sign
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AUTHOR
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Paul D. Hanna, Jan 10 2008
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STATUS
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approved
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