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A133467
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a(n)=a(n-1)+6*a(n-2) for n>=2, a(0)=1, a(1)=2 .
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1
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1, 2, 8, 20, 68, 188, 596, 1724, 5300, 15644, 47444, 141308, 425972, 1273820, 3829652, 11472572, 34450484, 103285916, 309988820, 929704316, 2789637236, 8367863132, 25105686548, 75312865340, 225946984628, 677824176668
(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-6*x^2) .
a(n)=Sum_{k, 0<=k<=n+1}A122950(n+1,k)*5^(n+1-k). - Philippe DELEHAM (kolotoko(AT)wanadoo.fr), Jan 08 2008
a(n)=(4/5)*3^n+(1/5)*(-2)^n, with n>=0 [From Paolo P. Lava (paoloplava(AT)gmail.com), Nov 18 2008]
a(n)=0.8*3^n+0.2*(-2)^n [From Richard Choulet (richardchoulet(AT)yahoo.fr), Nov 19 2008]
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PROG
| sage: from sage.combinat.sloane_functions import recur_gen2b sage: it = recur_gen2b(1, 2, 1, 6, lambda n: 0) sage: [it.next() for i in xrange(0, 29)] - Zerinvary Lajos (zerinvarylajos(AT)yahoo.com), Jul 03 2008
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CROSSREFS
| Sequence in context: A081157 A099177 A100097 * A091004 A005559 A001471
Adjacent sequences: A133464 A133465 A133466 * A133468 A133469 A133470
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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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