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Search: id:A122112
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| A122112 |
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a(0)=1, a(1)=-2, a(n)=4*a(n-2)-a(n-1) for n>1. |
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+0
1
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| 1, -2, 6, -14, 38, -94, 246, -622, 1606, -4094, 10518, -26894, 68966, -176542, 452406, -1158574, 2968198, -7602494, 19475286, -49885262, 127786406, -327327454, 838473078, -2147782894, 5501675206, -14092806782, 36099507606, -92470734734
(list; graph; listen)
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OFFSET
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0,2
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FORMULA
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a(n)=(-1)^n*A026597(n) . a(n)=Sum_[k, 0<=k<=n}(-2)^(n-k)*A055830(n,k) . G.f.: (1-x)/(1+x-4*x^2)
a(n)=(1/2)*[(-1/2)-(1/2)*sqrt(17)]^n+(3/34)*[(-1/2)-(1/2)*sqrt(17)]^n*sqrt(17)-(3/34)*sqrt(17)*[(-1 /2)+(1/2)*sqrt(17)]^n+(1/2)*[(-1/2)+(1/2)*sqrt(17)]^n, with n>=0 [From Paolo P. Lava (ppl(AT)spl.at), Nov 19 2008]
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CROSSREFS
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Sequence in context: A071636 A100067 A026597 this_sequence A000634 A006654 A127546
Adjacent sequences: A122109 A122110 A122111 this_sequence A122113 A122114 A122115
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KEYWORD
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sign
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AUTHOR
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Philippe DELEHAM (kolotoko(AT)wanadoo.fr), Oct 18 2006
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EXTENSIONS
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Corrected by T. D. Noe (noe(AT)sspectra.com), Nov 07 2006
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