A212110 Number of (w,x,y,z) with all terms in {1,...,n} and w*x+y*z=n^2.

0, 0, 4, 8, 16, 18, 40, 28, 56, 56, 82, 56, 152, 74, 148, 150, 176, 110, 276, 136, 334, 260, 296, 180, 516, 268, 378, 360, 528, 266, 850, 300, 624, 536, 614, 578, 1084, 394, 768, 714, 1154, 478, 1432, 528, 1140, 1082, 1052, 620, 1860, 816, 1464

Offset

0,3

Comments

Every term is even. For a guide to related sequences, see A211795.

Links

Table of n, a(n) for n=0..50.

Mathematica

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, 60]]   (* A212110 *)
%/2   (* integers *)
(* Peter J. C. Moses, Apr 13 2012 *)

Crossrefs

Cf. A211795.

Sequence in context: A195382 A211413 A181310 * A033310 A355660 A312785

Adjacent sequences: A212107 A212108 A212109 * A212111 A212112 A212113

Keyword

nonn

Author

Clark Kimberling, May 07 2012

Status

approved