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A198080
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a(n) = (3^(3*n + 3)- 26*n - 27)/169.
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1
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0, 4, 116, 3144, 84904, 2292428, 61895580, 1671180688, 45121878608, 1218290722452, 32893849506244, 888133936668632, 23979616290053112, 647449639831434076, 17481140275448720108, 471990787437115442976, 12743751260802116960416, 344081284041657157931300
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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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a(n) = (3^(3*n + 3) - 26*n - 27)/169.
G.f.: -4*x / ( (27*x-1)*(x-1)^2 ). - R. J. Mathar, Oct 25 2011
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EXAMPLE
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a(1) = (3^(3 + 3) - 26 - 27)/169 = 676/169 = 4.
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MAPLE
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for n from 0 to 30 do:x:=(3^(3*n+3) - 26*n - 27)/169 : printf(`%d, `, x):od:
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MATHEMATICA
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LinearRecurrence[{29, -55, 27}, {0, 4, 116}, 50] (* Vincenzo Librandi, Nov 25 2011 *)
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PROG
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(Magma) I:=[0, 4, 116]; [n le 3 select I[n] else 29*Self(n-1)-55*Self(n-2)+27*Self(n-3): n in [1..20]]; // Vincenzo Librandi, Nov 25 2011
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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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