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A074545
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a(n) = 2^n + 7^n + 9^n.
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1
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3, 18, 134, 1080, 8978, 75888, 649154, 5606640, 48811778, 427774608, 3769260674, 33358388400, 296270827778, 2638754846928, 23555015544194, 210638693637360, 1886253119486978, 16909812213784848, 151723048895171714
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listen;
history;
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internal format)
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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/(1-2*x) + 1/(1-7*x) + 1/(1-9*x).
E.g.f.: exp(2*x) + exp(7*x) + exp(9*x). (End)
a(n) = 18*a(n-1) - 95*a(n-2) + 126*a(n-3).
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MATHEMATICA
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Table[2^n + 7^n + 9^n, {n, 0, 20}]
LinearRecurrence[{18, -95, 126}, {3, 18, 134}, 20] (* Harvey P. Dale, Apr 13 2019 *)
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PROG
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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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