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A133672
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a(n)=a(n-1)-81*a(n-2), a(0)=1, a(1)=9 .
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1
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1, 9, -72, -801, 5031, 69912, -337599, -6000471, 21345048, 507383199, -1221565689, -42319604808, 56627216001, 3484515205449, -1102289290632, -283348020932001, -194062588390809, 22757127107101272, 38476196766756801, -1804851098908446231
(list; graph; refs; listen; history; internal format)
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OFFSET
| 0,2
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FORMULA
| G.f.:(1+8*x)/(1-x+81*x^2).
a(n)=Sum_{k, 0<=k<=n}A133607(n,k)*9^k. - Philippe DELEHAM (kolotoko(AT)wanadoo.fr), Dec 30 2007
a(n)=-(1/38)*I*sqrt(323)*[1/2+(1/2)*I*sqrt(323)]^n+(1/2)*[1/2-(1/2)*I*sqrt(323)]^n+(1 /38)*I*sqrt(323)*[1/2-(1/2)*I*sqrt(323)]^n+(1/2)*[1/2+(1/2)*I*sqrt(323)]^n, with n>=0 and I=sqrt(-1) [From Paolo P. Lava (paoloplava(AT)gmail.com), Aug 28 2008]
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CROSSREFS
| Sequence in context: A001809 A006135 A180836 * A043079 A099973 A091986
Adjacent sequences: A133669 A133670 A133671 * A133673 A133674 A133675
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KEYWORD
| easy,sign
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AUTHOR
| Philippe DELEHAM (kolotoko(AT)wanadoo.fr), Dec 29 2007
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