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1, 4, 10, 20, 33, 48, 64, 82, 103, 128, 156, 186, 217, 250, 286, 326, 369, 414, 460, 508, 559, 614, 672, 732, 793, 856, 922, 992, 1065, 1140, 1216, 1294, 1375, 1460, 1548, 1638, 1729, 1822, 1918, 2018, 2121
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internal format)
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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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G.f.: ( -1-x-x^2-2*x^3 ) / ( (1+x)*(x^2-x+1)*(x-1)^3 ). - R. J. Mathar, Dec 15 2015
a(n) = (9 + 72*n + 30*n^2 + 32*cos((n + 1)*Pi/3) - (-1)^n)/24. - Greg Dresden, Jun 22 2021
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MATHEMATICA
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LinearRecurrence[{3, -3, 0, 3, -3, 1}, {1, 4, 10, 20, 33, 48}, 50] (* Harvey P. Dale, Jun 14 2021 *)
Table[(9 + 72n + 30n^2 + 32Cos[(n + 1)Pi/3] - (-1)^n)/24, {n, 0, 40}] (* Greg Dresden, Jun 22 2021 *)
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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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