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Search: id:A133673
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| A133673 |
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a(n) = n*L(n) + (n-1)*L(n-1) where L(n) is the Lucas number. |
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+0
1
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| 7, 18, 40, 83, 163, 311, 579, 1060, 1914, 3419, 6053, 10637, 18575, 32262, 55772, 96019, 164711, 281635, 480171, 816536
(list; graph; listen)
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OFFSET
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2,1
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COMMENT
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For n>2, two evens followed by four odds.
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FORMULA
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G.f.: -x^2*(-7-4*x+3*x^2+x^3)/(x^2+x-1)^2. a(n)=2*a(n-1)+a(n-2)-2*a(n-3)-a(n-4). a(n)=A146005(n)+A146005(n-1). [From R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Jul 08 2009, Jul 13 2009]
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EXAMPLE
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If n=2 then a(n) = 7
If n=21 then a(n) = 816536
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CROSSREFS
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Cf. A000032, A136376.
Sequence in context: A156619 A033537 A000566 this_sequence A023166 A002764 A124053
Adjacent sequences: A133670 A133671 A133672 this_sequence A133674 A133675 A133676
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KEYWORD
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nonn
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AUTHOR
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Parthasarathy Nambi (PachaNambi(AT)yahoo.com), Dec 29 2007
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EXTENSIONS
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Typo in A-numbers corrected by R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Jul 13 2009
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