A212052 Number of (w,x,y,z) with all terms in {1,...,n} and 4w*x=5*y*z.

0, 0, 0, 0, 0, 18, 26, 30, 46, 52, 104, 112, 148, 156, 176, 278, 342, 354, 406, 418, 562, 602, 642, 658, 794, 988, 1040, 1090, 1190, 1210, 1526, 1550, 1726, 1794, 1858, 2152, 2368, 2396, 2468, 2548, 2980, 3012, 3212, 3244, 3408, 3890, 3982, 4018

Offset: 0

Author

Clark Kimberling, Apr 29 2012

Keywords

• nonn

Comments

See A211795 for a guide to related sequences.

Crossrefs

Cf. A211795.

Programs

Mathematica

t = Compile[{{n, _Integer}}, Module[{s = 0},
(Do[If[4 w*x == 5 y*z, s = s + 1],
{w, 1, #}, {x, 1, #}, {y, 1, #}, {z, 1, #}] &[n]; s)]];
Map[t[#] &, Range[0, 50]] (* A212052 *)
%/2  (* integers *)
(* Peter J. C. Moses, Apr 13 2012 *)