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A052833
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Expansion of e.g.f.: (log(2-exp(x)))^2.
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1
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0, 0, 2, 12, 72, 500, 4080, 38668, 419160, 5124708, 69831360, 1049972924, 17273719848, 308714206996, 5956836347280, 123437573728620, 2734197673727736, 64473939310567364, 1612626113517932640, 42645398700110627356, 1188880256538133537224, 34849264499702702749812
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OFFSET
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0,3
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COMMENTS
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Previous name was: A simple grammar.
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LINKS
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FORMULA
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E.g.f.: log(-1/(-2+exp(x)))^2.
a(n) ~ (n-1)! * 2*(log(n) + gamma - log(2) - log(log(2)))/log(2)^n, where gamma is Euler-Mascheroni constant (A001620). - Vaclav Kotesovec, Sep 30 2013
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MAPLE
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spec := [S, {B=Set(Z, 1 <= card), C=Cycle(B), S=Prod(C, C)}, labeled]: seq(combstruct[count](spec, size=n), n=0..20);
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MATHEMATICA
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CoefficientList[Series[Log[2-E^x]^2, {x, 0, 20}], x]* Range[0, 20]! (* Vaclav Kotesovec, Sep 30 2013 *)
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PROG
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(PARI) x='x+O('x^30); concat([0, 0], Vec(serlaplace((log(2-exp(x)))^2))) \\ G. C. Greubel, Sep 05 2018
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CROSSREFS
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KEYWORD
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easy,nonn
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AUTHOR
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encyclopedia(AT)pommard.inria.fr, Jan 25 2000
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EXTENSIONS
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STATUS
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approved
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