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A133667
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a(n)=a(n-1)-25*a(n-2), a(0)=1, a(1)=5 .
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1
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1, 5, -20, -145, 355, 3980, -4895, -104395, 17980, 2627855, 2178365, -63518020, -117976895, 1469973605, 4419395980, -32329944145, -142814843645, 665433759980, 4235804851105, -12400039148395, -118295160426020, 191705818283855
(list; graph; refs; listen; history; internal format)
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OFFSET
| 0,2
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FORMULA
| G.f.:(1+4*x)/(1-x+25*x^2) .
a(n)=Sum_{k, 0<=k<=n}A133607(n,k)*5^k. - Philippe DELEHAM (kolotoko(AT)wanadoo.fr), Dec 29 2007
a(n)=(3/22)*I*sqrt(11)*[1/2-(3/2)*I*sqrt(11)]^n+(1/2)*[1/2-(3/2)*I*sqrt(11)]^n+(1/2)*[1/2 +(3/2)*I*sqrt(11)]^n-(3/22)*I*sqrt(11)*[1/2+(3/2)*I*sqrt(11)]^n, with n>=0 and I=sqrt(-1) [From Paolo P. Lava (paoloplava(AT)gmail.com), Aug 27 2008]
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CROSSREFS
| Sequence in context: A024066 A009569 A061964 * A205338 A197857 A197741
Adjacent sequences: A133664 A133665 A133666 * A133668 A133669 A133670
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KEYWORD
| easy,sign
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AUTHOR
| Philippe DELEHAM (kolotoko(AT)wanadoo.fr), Dec 28 2007
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