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A022270
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a(n) = n*(13*n - 1)/2.
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3
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0, 6, 25, 57, 102, 160, 231, 315, 412, 522, 645, 781, 930, 1092, 1267, 1455, 1656, 1870, 2097, 2337, 2590, 2856, 3135, 3427, 3732, 4050, 4381, 4725, 5082, 5452, 5835, 6231, 6640, 7062, 7497, 7945, 8406, 8880, 9367, 9867, 10380, 10906, 11445
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OFFSET
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0,2
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LINKS
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FORMULA
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a(0)=0, a(1)=6, a(2)=25; for n>2, a(n) = 3*a(n-1) - 3*a(n-2) + a(n-3). - Harvey P. Dale, Dec 02 2011
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MATHEMATICA
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Table[n (13 n - 1)/2, {n, 0, 40}] (* or *) LinearRecurrence[{3, -3, 1}, {0, 6, 25}, 40] (* Harvey P. Dale, Dec 02 2011 *)
CoefficientList[Series[x (6 + 7 x) / (1 - x)^3, {x, 0, 40}], x] (* Vincenzo Librandi, Mar 31 2015 *)
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PROG
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CROSSREFS
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Cf. similar sequences listed in A022288.
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KEYWORD
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nonn,easy
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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