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A212105
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Number of (w,x,y,z) with all terms in {1,...,n} and w > harmonic mean of {x,y,z}.
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3
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0, 0, 7, 45, 150, 373, 768, 1437, 2479, 4002, 6120, 9010, 12786, 17661, 23821, 31464, 40809, 52102, 65577, 81531, 100201, 121911, 146979, 175717, 208434, 245550, 287401, 334380, 386877, 445366, 510222, 581922, 660952, 747750, 842850
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OFFSET
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0,3
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COMMENTS
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A 4-tuple (w,x,y,z) is counted if 3/w>1/x+1/y+1/z.
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*(y*z + z*x + x*y) > 3 x*y*z, s = s + 1],
{w, 1, #}, {x, 1, #}, {y, 1, #}, {z, 1, #}] &[n]; s)]];
Map[t[#] &, Range[0, 40]] (* A212105 *)
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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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