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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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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, 1385262, 2345083, 3962185, 6682393, 11251543, 18916026, 31756624, 53243795, 89160619, 149135759, 249187923, 415946572, 693648930
(list; graph; refs; listen; history; internal format)
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OFFSET
| 2,1
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COMMENTS
| For n>2, two evens followed by four odds.
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LINKS
| Harvey P. Dale, Table of n, a(n) for n = 2..1000
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FORMULA
| 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
| If n=2 then a(n) = 7
If n=21 then a(n) = 816536
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MATHEMATICA
| Total/@Partition[Times@@@Table[{n, LucasL[n]}, {n, 30}], 2, 1] (* or *) LinearRecurrence[{2, 1, -2, -1}, {7, 18, 40, 83}, 30](* From Harvey P. Dale, Oct 21 2011 *)
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CROSSREFS
| Cf. A000032, A136376.
Sequence in context: A000566 A169677 A192751 * A023166 A002764 A124053
Adjacent sequences: A133670 A133671 A133672 * A133674 A133675 A133676
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KEYWORD
| nonn
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AUTHOR
| Parthasarathy Nambi (PachaNambi(AT)yahoo.com), Dec 29 2007
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EXTENSIONS
| Typo in A-numbers corrected by R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Jul 13 2009
More terms from Harvey P. Dale, Oct 21 2011
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