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A154516
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a(n) = 9n^2 - n.
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4
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8, 34, 78, 140, 220, 318, 434, 568, 720, 890, 1078, 1284, 1508, 1750, 2010, 2288, 2584, 2898, 3230, 3580, 3948, 4334, 4738, 5160, 5600, 6058, 6534, 7028, 7540, 8070, 8618, 9184, 9768, 10370, 10990, 11628, 12284, 12958, 13650, 14360
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OFFSET
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1,1
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COMMENTS
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The continued fraction expansion of sqrt(a(n)) is [3n-1; {1, 4, 1, 6n-2}]. For n=1, this collapses to [2; {1, 4}]. - Magus K. Chu, Sep 06 2022
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LINKS
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FORMULA
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MATHEMATICA
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PROG
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(Sage) [lucas_number1(3, 3*n, n) for n in range(0, 41)] # Zerinvary Lajos, Nov 20 2009
(Magma) I:=[8, 34, 78]; [n le 3 select I[n] else 3*Self(n-1)-3*Self(n-2)+1*Self(n-3): n in [1..50]]; // Vincenzo Librandi, Jan 30 2012
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CROSSREFS
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KEYWORD
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nonn,easy
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AUTHOR
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STATUS
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approved
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