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Search: id:A015533
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| A015533 |
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a(n) = 4 a(n-1) + 9 a(n-2). |
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+0
1
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| 0, 1, 4, 25, 136, 769, 4300, 24121, 135184, 757825, 4247956, 23812249, 133480600, 748232641, 4194255964, 23511117625, 131792774176, 738771155329, 4141219588900, 23213818753561, 130126251314344, 729429374039425
(list; graph; listen)
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OFFSET
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0,3
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FORMULA
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O.g.f.: -x/(-1+4*x+9*x^2). a(n)=-9^n*(A^n-B^n)/(2sqrt(13)) where A=-1/(2+sqrt(13)) and B=1/(sqrt(13)-2) . - R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Apr 29 2008
a(n)=Sum_{k, 0<=k<=n}A155161(n,k)*3^(n-k), n>=1 . [From Philippe DELEHAM (kolotoko(AT)wanadoo.fr), Jan 27 2009]
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PROGRAM
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(Other) sage: [lucas_number1(n, 4, -9) for n in xrange(0, 22)]# [From Zerinvary Lajos (zerinvarylajos(AT)yahoo.com), Apr 23 2009]
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CROSSREFS
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Sequence in context: A013582 A123660 A156701 this_sequence A079291 A072221 A055846
Adjacent sequences: A015530 A015531 A015532 this_sequence A015534 A015535 A015536
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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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