A212021 Number of (w,x,y,z) with all terms in {1,...,n} and 2w*x=3*y*z.

0, 0, 0, 8, 16, 20, 48, 56, 80, 132, 164, 176, 272, 288, 332, 436, 512, 532, 696, 720, 844, 1000, 1076, 1104, 1360, 1430, 1518, 1758, 1942, 1978, 2328, 2368, 2566, 2818, 2938, 3098, 3600, 3648, 3780, 4084, 4440, 4492, 4996, 5052, 5348, 5920

Offset: 0

Author

Clark Kimberling, Apr 28 2012

Keywords

• nonn

Comments

Each term is divisible by 2. See A211795 for a guide to related sequences.

Crossrefs

Cf. A211795.

Programs

Mathematica

t = Compile[{{n, _Integer}}, Module[{s = 0},
(Do[If[2 w*x == 3 y*z, s = s + 1],
{w, 1, #}, {x, 1, #}, {y, 1, #}, {z, 1, #}] &[n]; s)]];
Map[t[#] &, Range[0, 50]] (* A212021 *)
%/2  (* integers *)
(* Peter J. C. Moses, Apr 13 2012 *)