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A212061
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Number of (w,x,y,z) with all terms in {1,...,n} and w*x=(y*z)^2.
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2
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0, 1, 3, 5, 12, 14, 18, 20, 30, 45, 49, 51, 65, 67, 71, 75, 106, 108, 134, 136, 150, 154, 158, 160, 180, 215, 219, 241, 255, 257, 265, 267, 307, 311, 315, 319, 392, 394, 398, 402, 422, 424, 432, 434, 448, 478, 482, 484, 540, 599, 657, 661, 675, 677
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OFFSET
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0,3
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COMMENTS
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For a guide to related sequences, see A211795.
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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 == (y*z)^2, s = s + 1],
{w, 1, #}, {x, 1, #}, {y, 1, #}, {z, 1, #}] &[n]; s)]];
Map[t[#] &, Range[0, 50]] (* A212061 *)
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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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