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A133469
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a(n)=a(n-1)+7*a(n-2) for n>=2, a(0)=1, a(1)=2 .
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1
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1, 2, 9, 23, 86, 247, 849, 2578, 8521, 26567, 86214, 272183, 875681, 2780962, 8910729, 28377463, 90752566, 289394807, 924662769, 2950426418, 9423065801, 30076050727, 96037511334, 306569866423, 978832445761, 3124821510722
(list; graph; refs; listen; history; internal format)
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OFFSET
| 0,2
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FORMULA
| G.f.: (1+x)/(1-x-7*x^2) .
a(n)=Sum_{k, 0<=k<=n+1}A122950(n+1,k)*6^(n+1-k). - Philippe DELEHAM (kolotoko(AT)wanadoo.fr), Jan 08 2008
a(n)=(1/2)*[(1/2)+(1/2)*sqrt(29)]^n+(3/58)*sqrt(29)*[(1/2)+(1/2)*sqrt(29)]^n-(3/58)*sqrt(29)*[(1/2)-(1 /2)*sqrt(29)]^n+(1/2)*[(1/2)-(1/2)*sqrt(29)]^n, with n>=0 [From Paolo P. Lava (paoloplava(AT)gmail.com), Nov 18 2008]
a(n)= ((29+3*sqrt(29))/58)*(0.5+0.5*sqrt(29))^n+((29-3*sqrt(29))/58)*(0.5-0.5*sqrt(29))^n [From Richard Choulet (richardchoulet(AT)yahoo.fr), Nov 20 2008]
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CROSSREFS
| Sequence in context: A154118 A115185 A091107 * A075714 A101583 A204556
Adjacent sequences: A133466 A133467 A133468 * A133470 A133471 A133472
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KEYWORD
| easy,nonn
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AUTHOR
| Philippe DELEHAM (kolotoko(AT)wanadoo.fr), Jan 03 2008
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