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Search: id:A015524
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| A015524 |
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a(n) = 3 a(n-1) + 7 a(n-2). |
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+0
3
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| 0, 1, 3, 16, 69, 319, 1440, 6553, 29739, 135088, 613437, 2785927, 12651840, 57457009, 260933907, 1185000784, 5381539701, 24439624591, 110989651680, 504046327177, 2289066543291, 10395523920112, 47210037563373
(list; graph; listen)
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OFFSET
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0,3
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COMMENT
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Linear 2nd order recurrence.
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FORMULA
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O.g.f.: -x/(-1+3*x+7*x^2). a(n)=14^n*[1/A^n -(-1)^n/B^n]/sqrt(37) where A=sqrt(37)-3 = A010491-3 and B = sqrt(37)+3=A010491+3 - R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Apr 21 2008.
O.g.f.: -x/(-1+3*x+7*x^2). a(n)=-14^n*(A^n-B^n)/sqrt(37) where A=-1/(3+sqrt(37)) and B=1/(sqrt(37)-3) . - R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Apr 29 2008
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PROGRAM
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(Other) sage: [lucas_number1(n, 3, -7) for n in xrange(0, 23)]# [From Zerinvary Lajos (zerinvarylajos(AT)yahoo.com), Apr 22 2009]
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CROSSREFS
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Sequence in context: A062960 A044046 A000269 this_sequence A012279 A037098 A038602
Adjacent sequences: A015521 A015522 A015523 this_sequence A015525 A015526 A015527
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KEYWORD
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nonn,easy
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AUTHOR
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Olivier Gerard (olivier.gerard(AT)gmail.com)
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