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A131475
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a(n) = floor(n/2) * floor(n^2/2).
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1
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0, 0, 2, 4, 16, 24, 54, 72, 128, 160, 250, 300, 432, 504, 686, 784, 1024, 1152, 1458, 1620, 2000, 2200, 2662, 2904, 3456, 3744, 4394, 4732, 5488, 5880, 6750, 7200, 8192, 8704, 9826, 10404, 11664, 12312, 13718, 14440, 16000, 16800
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OFFSET
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0,3
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LINKS
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FORMULA
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G.f.: 2*x^2*(1 + x + 3*x^2 + x^3)/((1+x)^3*(1-x)^4). - R. J. Mathar, Dec 19 2008
a(n) = a(n-1) + 3*a(n-2) - 3*a(n-3) - 3*a(n-4) + 3*a(n-5) + a(n-6) - a(n-7).
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PROG
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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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