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A036068
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Expansion of (-1+1/(1-3*x)^3)/(9*x).
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6
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1, 6, 30, 135, 567, 2268, 8748, 32805, 120285, 433026, 1535274, 5373459, 18600435, 63772920, 216827928, 731794257, 2453663097, 8178876990, 27119434230, 89494132959, 294052151151, 962352494676, 3138105960900, 10198844372925
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OFFSET
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0,2
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COMMENTS
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G.f. for a(n)=A027472(n+3), n >= 0, is 1/(1-3*x)^3.
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LINKS
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FORMULA
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a(n) = 3^(n-1)*binomial(n+3, 2); G.f.: (-1+(1-3*x)^(-3))/(x*3^2)=(1-3*x+3*x^2)/(1-3*x)^3.
D-finite with recurrence: (n+1)*a(n) +3*(-n-3)*a(n-1)=0. - R. J. Mathar, Jan 28 2020
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MATHEMATICA
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CoefficientList[Series[((1/(1-3x))^3-1)/(9x), {x, 0, 30}], x] (* Harvey P. Dale, Nov 26 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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STATUS
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approved
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