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A052769
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E.g.f.: x^3*(exp(x)-1)^2.
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2
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0, 0, 0, 0, 0, 120, 720, 2940, 10080, 31248, 90720, 251460, 673200, 1753752, 4468464, 11176620, 27518400, 66838560, 160422336, 381014676, 896518800, 2091893160, 4844402640, 11142147324, 25467789600, 57881367600, 130862253600, 294440105700, 659545876080
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OFFSET
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0,6
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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.: x^3*exp(x)^2 - 2*x^3*exp(x) + x^3.
Recurrence: {a(1)=0, a(2)=0, a(4)=0, a(3)=0, (2*n^2+6*n+4)*a(n)+(-3*n^2+12)*a(n+1)+(-3*n+n^2+2)*a(n+2), a(5)= 120}.
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MAPLE
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spec := [S, {B=Set(Z, 1 <= card), S=Prod(Z, Z, Z, B, B)}, labeled]: seq(combstruct[count](spec, size=n), n=0..20);
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MATHEMATICA
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CoefficientList[Series[x^3*(E^x-1)^2, {x, 0, 20}], x]* Range[0, 20]! (* Vaclav Kotesovec, Sep 30 2013 *)
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PROG
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(PARI) seq(n)={Vec(serlaplace(x^3*(exp(x + O(x^(n-3)))-1)^2), -(n+1))} \\ Andrew Howroyd, Jan 02 2020
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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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