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A168150
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Inverse binomial transform of A026741.
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1
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0, 1, -1, 3, -8, 20, -48, 112, -256, 576, -1280, 2816, -6144, 13312, -28672, 61440, -131072, 278528, -589824, 1245184, -2621440, 5505024, -11534336, 24117248, -50331648, 104857600, -218103808, 452984832, -939524096, 1946157056, -4026531840, 8321499136, -17179869184
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OFFSET
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0,4
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LINKS
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FORMULA
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a(n) = -4*a(n-1) -4*a(n-2) = (-2)^(n-3)*n, n>3.
G.f.: x*(1 + 3*x + 3*x^2)/(1 + 2*x)^2. (End)
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MATHEMATICA
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Join[{0, 1, -1, 3}, LinearRecurrence[{-4, -4}, {-8, 20}, 50]] (* G. C. Greubel, Jul 14 2016 *)
CoefficientList[Series[x (1 + 3 x + 3 x^2) / (1 + 2 x)^2, {x, 0, 33}], x] (* Vincenzo Librandi, Jul 15 2016 *)
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PROG
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(PARI) a(n)=(-2)^if(n>1, n-3)*n \\ M. F. Hasler, Jan 25 2012
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CROSSREFS
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KEYWORD
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sign,easy
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AUTHOR
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EXTENSIONS
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Comments turned into formulas, out-of-scope material moved to A026741 by R. J. Mathar, Nov 23 2009
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STATUS
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approved
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