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A113854
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a(n) = sum(2^(A047240(i)-1), i=1..n).
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2
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1, 3, 35, 99, 227, 2275, 6371, 14563, 145635, 407779, 932067, 9320675, 26097891, 59652323, 596523235, 1670265059, 3817748707, 38177487075, 106896963811, 244335917283, 2443359172835, 6841405683939, 15637498706147
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OFFSET
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1,2
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LINKS
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FORMULA
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G.f.: x*(1+2*x+32*x^2)/((-1+x)*(-1+4*x)*(1+4*x+16*x^2)). - Vaclav Kotesovec, Nov 28 2012
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EXAMPLE
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MATHEMATICA
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a = {}; s = 0; For[n = 1, n < 48, n++, If[Length[Intersection[{Mod[n, 6]}, {1, 2, 0}]] > 0, s = s + 2^(n - 1); AppendTo[a, s]]]; a
CoefficientList[Series[(1 + 2 x + 32 x^2)/((-1 + x) (-1 + 4 x) (1 + 4 x + 16 x^2)), {x, 0, 25}], x] (* Vincenzo Librandi, May 20 2013 *)
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CROSSREFS
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KEYWORD
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nonn,easy
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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