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A115328
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E.g.f: exp(x/(1-3*x))/sqrt(1-9*x^2).
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1
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1, 1, 16, 100, 2116, 27556, 732736, 14776336, 476112400, 13013333776, 494512742656, 17019717246016, 747017670477376, 30923039616270400, 1542024562112889856, 74433082892402872576, 4161241771884669788416
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OFFSET
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0,3
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COMMENTS
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Term-by-term square of sequence with e.g.f.: exp(x+m/2*x^2) is given by e.g.f.: exp(x/(1-m*x))/sqrt(1-m^2*x^2) for all m.
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LINKS
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FORMULA
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Equals term-by-term square of A115327 which has e.g.f.: exp(x+3/2*x^2).
D-finite with recurrence: a(n) = (3*n-2)*a(n-1) - 27*(n-1)*(n-2)^2*a(n-3) + 3*(n-1)*(3*n-2)*a(n-2). - Vaclav Kotesovec, Jun 26 2013
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MATHEMATICA
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CoefficientList[Series[E^(x/(1-3*x))/Sqrt[1-9*x^2], {x, 0, 20}], x]* Range[0, 20]! (* Vaclav Kotesovec, Jun 26 2013 *)
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PROG
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(PARI) a(n)=local(m=3); n!*polcoeff(exp(x/(1-m*x+x*O(x^n)))/sqrt(1-m^2*x^2+x*O(x^n)), n)
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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STATUS
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approved
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