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A152299
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A threes sequence that gets more even factors out: a(n)=(3^n - 1)*(3^n + 1)/2^(4 - Mod[n, 2]).
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0
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1, 5, 91, 410, 7381, 33215, 597871, 2690420, 48427561, 217924025, 3922632451, 17651846030, 317733228541, 1429799528435, 25736391511831, 115813761803240, 2084647712458321, 9380914706062445, 168856464709124011
(list; graph; refs; listen; history; internal format)
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OFFSET
| 0,2
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FORMULA
| a(n)=(3^n - 1)*(3^n + 1)/2^(4 - Mod[n, 2]).
a(n)=82*a(n-2)-81*a(n-4). G.f.: (1+5x+9x^2)/((1-x)(1-9x)(1+x)(1+9x)). [From R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Dec 04 2008]
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MATHEMATICA
| Clear[a, n];
a[n_] :=(3^n - 1)*(3^n + 1)/2^(4 - Mod[n, 2]);
Table[a[n], {n, 0, 30}]
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CROSSREFS
| A003462, A002452
Sequence in context: A037297 A158073 A038636 * A091281 A109625 A024069
Adjacent sequences: A152296 A152297 A152298 * A152300 A152301 A152302
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KEYWORD
| nonn
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AUTHOR
| Roger L. Bagula (rlbagulatftn(AT)yahoo.com), Dec 02 2008
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