A212052 - OEIS

%I #5 Dec 04 2016 19:46:29

%S 0,0,0,0,0,18,26,30,46,52,104,112,148,156,176,278,342,354,406,418,562,

%T 602,642,658,794,988,1040,1090,1190,1210,1526,1550,1726,1794,1858,

%U 2152,2368,2396,2468,2548,2980,3012,3212,3244,3408,3890,3982,4018

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

%C See A211795 for a guide to related sequences.

%t t = Compile[{{n, _Integer}}, Module[{s = 0},

%t (Do[If[4 w*x == 5 y*z, s = s + 1],

%t {w, 1, #}, {x, 1, #}, {y, 1, #}, {z, 1, #}] &[n]; s)]];

%t Map[t[#] &, Range[0, 50]] (* A212052 *)

%t %/2  (* integers *)

%t (* _Peter J. C. Moses_, Apr 13 2012 *)

%Y Cf. A211795.

%K nonn

%O 0,6

%A _Clark Kimberling_, Apr 29 2012