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A211797
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Number of 4-tuples (w,x,y,z) with all terms in {1,...,n} and w*x>2*y*z.
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3
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0, 0, 1, 15, 55, 156, 338, 666, 1159, 1905, 2950, 4399, 6275, 8748, 11847, 15721, 20450, 26228, 33078, 41271, 50799, 61947, 74832, 89674, 106480, 125659, 147291, 171618, 198767, 229139, 262698, 300007, 340983, 386100, 435544, 489598
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OFFSET
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0,4
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COMMENTS
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See A211795 for a guide to related sequences.
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LINKS
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MATHEMATICA
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t = Compile[{{n, _Integer}}, Module[{s = 0},
(Do[If[w*x > 2 y*z, s = s + 1], {w, 1, #},
{x, 1, #}, {y, 1, #}, {z, 1, #}] &[n]; s)]];
Map[t[#] &, Range[0, 40]] (* A211797 *)
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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STATUS
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approved
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