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A011898
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a(n) = floor(n*(n-1)*(n-2)/16).
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1
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0, 0, 0, 0, 1, 3, 7, 13, 21, 31, 45, 61, 82, 107, 136, 170, 210, 255, 306, 363, 427, 498, 577, 664, 759, 862, 975, 1096, 1228, 1370, 1522, 1685, 1860, 2046, 2244, 2454, 2677, 2913, 3163, 3427, 3705, 3997, 4305
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OFFSET
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0,6
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LINKS
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Index entries for linear recurrences with constant coefficients, signature (3, -3, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, -3, 3, -1).
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FORMULA
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a(n) = 3*a(n-1) - 3*a(n-2) + a(n-3) + a(n-16) - 3*a(n-17) + 3*a(n-18) - a(n-19).
G.f.: x^4*(1+x^2+2*x^6-2*x^7+3*x^8-x^9+x^11+x^12-x^13+x^14) / ( (-1+x)^4*(1+x)*(1+x^2)*(1+x^4)*(1+x^8) ). (End)
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MATHEMATICA
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Table[Floor[(n(n-1)(n-2))/16], {n, 0, 50}] (* Harvey P. Dale, May 16 2012 *)
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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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