A212051 Number of (w,x,y,z) with all terms in {1,...,n} and 3w*x=5*y*z.

0, 0, 0, 0, 0, 16, 28, 32, 40, 52, 112, 120, 164, 172, 192, 280, 310, 322, 398, 410, 580, 644, 680, 696, 816, 1004, 1048, 1138, 1218, 1238, 1592, 1616, 1702, 1798, 1854, 2138, 2394, 2422, 2486, 2598, 3068, 3100, 3368, 3400, 3536, 3976, 4056

Offset: 0

Author

Clark Kimberling, Apr 29 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[3 w*x == 5 y*z, s = s + 1],
{w, 1, #}, {x, 1, #}, {y, 1, #}, {z, 1, #}] &[n]; s)]];
Map[t[#] &, Range[0, 50]] (* A212051 *)
%/2  (* integers *)
(* Peter J. C. Moses, Apr 13 2012 *)