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Search: id:A133669
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| A133669 |
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a(n)=a(n-1)-49*a(n-2), a(0)=1, a(1)=7 . |
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+0
2
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| 1, 7, -42, -385, 1673, 20538, -61439, -1067801, 1942710, 54264959, -40927831, -2699910822, -694447103, 131601183175, 165629091222, -6282828884353, -14398654354231
(list; graph; listen)
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OFFSET
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0,2
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FORMULA
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G.f.:(1+6*x)/(1-x+49*x^2) .
a(n)=Sum_{k, 0<=k<=n}A133607(n,k)*7^k. - Philippe DELEHAM (kolotoko(AT)wanadoo.fr), Dec 30 2007
a(n)=(1/30)*I*[1/2-(1/2)*I*sqrt(195)]^n*sqrt(195)+(1/2)*[1/2-(1/2)*I*sqrt(195)]^n+(1/2) *[1/2+(1/2)*I*sqrt(195)]^n-(1/30)*I*[1/2+(1/2)*I*sqrt(195)]^n*sqrt(195), with n>=0 and I=sqrt(-1) [From Paolo P. Lava (ppl(AT)spl.at), Aug 28 2008]
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CROSSREFS
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Sequence in context: A073506 A025593 A048862 this_sequence A043064 A045800 A159254
Adjacent sequences: A133666 A133667 A133668 this_sequence A133670 A133671 A133672
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KEYWORD
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easy,sign
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AUTHOR
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Philippe DELEHAM (kolotoko(AT)wanadoo.fr), Dec 28 2007
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