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A165625
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a(n)=(5/3)*(1+2*(-5)^(n-1)).
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1
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1, 5, -15, 85, -415, 2085, -10415, 52085, -260415, 1302085, -6510415, 32552085, -162760415, 813802085, -4069010415, 20345052085, -101725260415, 508626302085, -2543131510415, 12715657552085, -63578287760415
(list; graph; refs; listen; history; internal format)
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OFFSET
| 0,2
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FORMULA
| a(n)=(-5)*a(n-1)+10 with a(0)=1. a(0)=1, a(1)=5, a(n)=5*a(n-2)-4*a(n-1). G.f.: (1+9x)/(1+4x-5x^2). a(n)= Sum_{k, 0<=k<=n} A112555(n,k)*4^(n-k).
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CROSSREFS
| Cf. A083217, A084247, A165553, A165622
Sequence in context: A183937 A030487 A165470 * A058820 A054363 A184438
Adjacent sequences: A165622 A165623 A165624 * A165626 A165627 A165628
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KEYWORD
| easy,sign
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AUTHOR
| Philippe DELEHAM (kolotoko(AT)wanadoo.fr), Sep 22 2009
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