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A082413
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a(n) = (2*9^n + 3^n)/3.
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3
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1, 7, 57, 495, 4401, 39447, 354537, 3189375, 28700001, 258286887, 2324542617, 20920765455, 188286534801, 1694577750327, 15251196564297, 137260759512735, 1235346806916801, 11118121176157767, 100063090327139577, 900567812169415215
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OFFSET
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0,2
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COMMENTS
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LINKS
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FORMULA
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G.f.: (1-5*x)/((1-3*x)*(1-9*x));
E.g.f.: (2*exp(9*x) + exp(3*x))/3.
a(n) = (2*9^n + 3^n)/3.
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MAPLE
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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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