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A248216
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a(n) = 6^n - 2^n.
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4
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0, 4, 32, 208, 1280, 7744, 46592, 279808, 1679360, 10077184, 60465152, 362795008, 2176778240, 13060685824, 78364147712, 470184951808, 2821109841920, 16926659313664, 101559956406272, 609359739486208, 3656158439014400, 21936950638280704
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OFFSET
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0,2
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LINKS
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FORMULA
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G.f.: 4*x/((1-2*x)*(1-6*x)).
a(n) = 8*a(n-1) - 12*a(n-2).
E.g.f.: exp(6*x) - exp(2*x) = 2*exp(4*x)*sinh(2*x). - G. C. Greubel, Feb 09 2021
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MATHEMATICA
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Table[6^n - 2^n, {n, 0, 25}] (* or *) CoefficientList[Series[4x/((1-2x)(1-6x)), {x, 0, 30}], x]
LinearRecurrence[{8, -12}, {0, 4}, 30] (* Harvey P. Dale, Dec 21 2019 *)
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PROG
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(Magma) [6^n-2^n: n in [0..25]];
(Sage) [2^n*(3^n -1) for n in (0..25)] # G. C. Greubel, Feb 09 2021
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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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STATUS
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approved
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