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A128533
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F(n)*L(n+2) where F=Fibonacci and L=Lucas numbers.
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4
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0, 4, 7, 22, 54, 145, 376, 988, 2583, 6766, 17710, 46369, 121392, 317812, 832039, 2178310, 5702886, 14930353, 39088168, 102334156, 267914295
(list; graph; refs; listen; history; internal format)
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OFFSET
| 0,2
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COMMENTS
| Generally, F(n)*L(n+k) = F(2*n + k) + F(k)*(-1)^(n+1):
if k=0 then sequence is A001906, if k=1 it is A081714.
a(n) = A186679(2*n). -- Reinhard Zumkeller, Feb 25 2011
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LINKS
| Index to sequences with linear recurrences with constant coefficients, signature (2,2,-1).
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FORMULA
| a(n) = F(2*(n+1)) + (-1)^(n+1), assuming F(0)=0 and L(0)=2
a(n)=2*a(n-1)+2*a(n-2)-a(n-3). G.f.: -x*(-4+x)/((1+x)*(x^2-3*x+1)). [From R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Apr 16 2009]
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EXAMPLE
| a(4)=54 because F(4)*L(6)=3*18.
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CROSSREFS
| Cf. A001906, A081714, A128534, A128535.
Sequence in context: A026548 A127361 A100098 * A162559 A126094 A073114
Adjacent sequences: A128530 A128531 A128532 * A128534 A128535 A128536
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KEYWORD
| easy,nonn
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AUTHOR
| Axel Harvey (ax(AT)hirsig.ca), Mar 08 2007
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