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A198080
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a(n)=(3^(3n+3)- 26n - 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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Second differences are four times the entries of A009971. - R. J. Mathar, Oct 25 2011
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LINKS
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Vincenzo Librandi, Table of n, a(n) for n = 0..700
Index entries for linear recurrences with constant coefficients, signature (29,-55,27).
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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
(PARI) a(n)=(3^(3*n+3)-26*n-27)/169 \\ Charles R Greathouse IV, Jul 06 2017
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CROSSREFS
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Sequence in context: A261457 A080482 A206689 * A272158 A194535 A030255
Adjacent sequences: A198077 A198078 A198079 * A198081 A198082 A198083
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KEYWORD
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nonn,easy
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AUTHOR
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Michel Lagneau, Oct 24 2011
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STATUS
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approved
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