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A212136
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Number of (w,x,y,z) with all terms in {1,...,n} and w*x+y*z>n^2.
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2
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0, 1, 7, 25, 60, 126, 222, 387, 599, 903, 1295, 1830, 2458, 3322, 4317, 5539, 6993, 8773, 10766, 13198, 15906, 19095, 22707, 26879, 31376, 36684, 42500, 49024, 56131, 64205, 72833, 82742, 93314, 104934, 117500, 131277, 146003, 162489
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OFFSET
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1,3
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COMMENTS
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A212136(n)+A212150(n)=n^4. For a guide to related sequences, see A211795.
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LINKS
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Table of n, a(n) for n=1..38.
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MATHEMATICA
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t = Compile[{{n, _Integer}}, Module[{s = 0},
(Do[If[w*x + y*z > n^2, s = s + 1],
{w, 1, #}, {x, 1, #}, {y, 1, #}, {z, 1, #}] &[n]; s)]];
Map[t[#] &, Range[0, 40]] (* A212136 *)
(* Peter J. C. Moses, Apr 13 2012 *)
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CROSSREFS
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Cf. A211795.
Sequence in context: A266709 A162264 A034135 * A213392 A061600 A098538
Adjacent sequences: A212133 A212134 A212135 * A212137 A212138 A212139
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KEYWORD
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nonn
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AUTHOR
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Clark Kimberling, May 07 2012
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STATUS
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approved
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