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A212110 Number of (w,x,y,z) with all terms in {1,...,n} and w*x+y*z=n^2. 1
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 (list; graph; refs; listen; history; text; internal format)
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

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Last modified December 3 09:03 EST 2022. Contains 358515 sequences. (Running on oeis4.)