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A074610
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a(n) = 3^n + 9^n.
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3
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2, 12, 90, 756, 6642, 59292, 532170, 4785156, 43053282, 387440172, 3486843450, 31381236756, 282430067922, 2541867422652, 22876797237930, 205891146443556, 1853020231898562, 16677181828806732, 150094635684419610
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OFFSET
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0,1
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LINKS
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FORMULA
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G.f.: 1/(1-3*x) + 1/(1-9*x).
E.g.f.: exp(3*x) + exp(9*x). (End)
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MATHEMATICA
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Table[3^n + 9^n, {n, 0, 25}]
LinearRecurrence[{12, -27}, {2, 12}, 20] (* Harvey P. Dale, May 18 2023 *)
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PROG
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(SageMath) [3^n+9^n for n in range(31)] # G. C. Greubel, Jan 13 2024
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CROSSREFS
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KEYWORD
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easy,nonn
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AUTHOR
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STATUS
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approved
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