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A074604
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a(n) = 2^n + 9^n.
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2
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2, 11, 85, 737, 6577, 59081, 531505, 4783097, 43046977, 387421001, 3486785425, 31381061657, 282429540577, 2541865836521, 22876792471345, 205891132127417, 1853020188917377, 16677181699797641, 150094635297261265
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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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a(n) = 9*a(n-1) - 2^n.
a(n) = 11*a(n-1) - 18*a(n-2), with a(0) = 2, a(1) = 11.
G.f.: 1/(1-2*x) + 1/(1-9*x).
E.g.f.: exp(2*x) + exp(9*x). (End)
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MATHEMATICA
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Table[2^n + 9^n, {n, 0, 25}]
LinearRecurrence[{11, -18}, {2, 11}, 26] (* Harvey P. Dale, Feb 28 2022 *)
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PROG
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(SageMath) [2^n+9^n for n in range(31)] # G. C. Greubel, Jan 16 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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