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Search: id:A128533
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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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+0
3
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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; listen)
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OFFSET
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0,2
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COMMENT
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Generally, F(n)*L(n+k) = F(2*n + k) + F(k)*(-1)^(n+1). If k=0 the sequence is A001906; if k=1 it is A081714.
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FORMULA
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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
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a(4)=54 because F(4)*L(6)=3*18.
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CROSSREFS
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Cf. A001906, A081714, A128534, A128535.
Sequence in context: A026548 A127361 A100098 this_sequence A162559 A126094 A073114
Adjacent sequences: A128530 A128531 A128532 this_sequence A128534 A128535 A128536
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KEYWORD
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easy,nonn
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AUTHOR
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Axel Harvey (ax(AT)hirsig.ca), Mar 08 2007
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