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A133666
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a(n)=a(n-1)-16*a(n-2), a(0)=1, a(1)=4 .
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1
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1, 4, -12, -76, 116, 1332, -524, -21836, -13452, 335924, 551156, -4823628, -13642124, 63535924, 281809908, -734764876, -5243723404, 6512514612, 90412089076, -12788144716, -1460381569932
(list; graph; refs; listen; history; internal format)
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OFFSET
| 0,2
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FORMULA
| G.f.:(1+3*x)/(1-x+16*x^2) .
a(n)=Sum_{k, 0<=k<=n}A133607(n,k)*4^k. - Philippe DELEHAM (kolotoko(AT)wanadoo.fr), Dec 29 2007
a(n)=-(1/6)*I*sqrt(7)*[(1/2)+(3/2)*I*sqrt(7)]^n+(1/6)*I*sqrt(7)*[(1/2)-(3/2)*I*sqrt(7)]^n +(1/2)*[(1/2)-(3/2)*I*sqrt(7)]^n+(1/2)*[(1/2)+(3/2)*I*sqrt(7)]^n, with n>=0 and I=sqrt(-1) [From Paolo P. Lava (paoloplava(AT)gmail.com), Nov 18 2008]
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CROSSREFS
| Sequence in context: A166746 A052558 A190340 * A078628 A165261 A027145
Adjacent sequences: A133663 A133664 A133665 * A133667 A133668 A133669
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KEYWORD
| easy,sign
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AUTHOR
| Philippe DELEHAM (kolotoko(AT)wanadoo.fr), Dec 28 2007, corrected Jan 04 2008
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