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A282022
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Start with 1; multiply alternately by 3 and 4.
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2
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1, 3, 12, 36, 144, 432, 1728, 5184, 20736, 62208, 248832, 746496, 2985984, 8957952, 35831808, 107495424, 429981696, 1289945088, 5159780352, 15479341056, 61917364224, 185752092672, 743008370688, 2229025112064, 8916100448256, 26748301344768, 106993205379072, 320979616137216
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OFFSET
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0,2
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COMMENTS
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Satisfies Benford's law.
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LINKS
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FORMULA
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O.g.f.: (1 + 3*x)/(1 - 12*x^2).
E.g.f.: sqrt(3)*sinh(2*sqrt(3)*x)/2 + cosh(2*sqrt(3)*x).
(End)
a(n) = 2^n * 3^(n/2) for n even.
a(n) = 2^(n-1) * 3^((n+1)/2) for n odd.
a(n) = 12*a(n-2) for n>1.
(End)
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MATHEMATICA
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LinearRecurrence[{0, 12}, {1, 3}, 30] (* Harvey P. Dale, Jun 19 2021 *)
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PROG
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(PARI) Vec((1 + 3*x) / (1 - 12*x^2) + O(x^30)) \\ Colin Barker, Feb 09 2017
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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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