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A083086
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a(n) = (2^(n+1) + (-4)^n)/3.
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5
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1, 0, 8, -16, 96, -320, 1408, -5376, 22016, -87040, 350208, -1396736, 5595136, -22364160, 89489408, -357892096, 1431699456, -5726535680, 22906667008, -91625619456, 366504574976, -1466014105600, 5864064811008, -23456242466816, 93825003421696, -375299946577920
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OFFSET
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0,3
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COMMENTS
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LINKS
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FORMULA
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a(n) = (2*2^n + (-4)^n)/3.
G.f.: (1+2*x)/((1+4*x)*(1-2*x).
E.g.f.: (2*exp(2*x) + exp(-4*x))/3.
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MATHEMATICA
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LinearRecurrence[{-2, 8}, {1, 0}, 41] (* G. C. Greubel, Feb 19 2023 *)
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PROG
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(SageMath) [(2^(n+1)+(-4)^n)/3 for n in range(41)] # G. C. Greubel, Feb 19 2023
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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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STATUS
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approved
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