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Search: id:A087451
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| A087451 |
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G.f.: (2-x)/((1+2x)(1-3x)); e.g.f.: exp(3x)+exp(-2x); a(n)=3^n+(-2)^n. |
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+0
3
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| 2, 1, 13, 19, 97, 211, 793, 2059, 6817, 19171, 60073, 175099, 535537, 1586131, 4799353, 14316139, 43112257, 129009091, 387682633, 1161737179, 3487832977, 10458256051, 31385253913, 94134790219, 282446313697, 847255055011
(list; graph; listen)
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OFFSET
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0,1
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COMMENT
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Generalized Lucas-Jacobsthal numbers.
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LINKS
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Drexel University, Generation X and Y
G. Everest, Y. Puri and T. Ward, Integer sequences counting periodic points
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FORMULA
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a(0)=2, a(1)=1, a(n)= a(n-1)+6a(n-2).
The sequence 1, 13, 19... is 3*3^n-2*(-2)^n.
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MATHEMATICA
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a[0] = 2; a[1] = 1; a[n_] := a[n] = a[n - 1] + 6a[n - 2]; a /@ Range[0, 25] (from Robert G. Wilson v (rgwv(at)rgwv.com), Feb 02 2006)
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CROSSREFS
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Cf. A014551, A087452.
Sequence in context: A113097 A032001 A118679 this_sequence A063558 A013020 A012906
Adjacent sequences: A087448 A087449 A087450 this_sequence A087452 A087453 A087454
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KEYWORD
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easy,nonn
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AUTHOR
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Paul Barry (pbarry(AT)wit.ie), Sep 06 2003
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