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A211787
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Number of (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, 1, 15, 66, 201, 469, 958, 1735, 2937, 4656, 7050, 10242, 14461, 19813, 26569, 34904, 45086, 57293, 71898, 89050, 109201, 132534, 159424, 190167, 225296, 264966, 309685, 359823, 415889, 478142, 547302, 623514, 707593, 799821
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OFFSET
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0,3
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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]] (* A211787 *)
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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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