A211920 Number of (w,x,y,z) with all terms in {1,...,n} and 2*w*x<3*y*z.

0, 1, 11, 50, 160, 387, 792, 1480, 2511, 4001, 6104, 8943, 12623, 17396, 23374, 30765, 39803, 50707, 63656, 79050, 96985, 117795, 141871, 169444, 200754, 236327, 276397, 321322, 371547, 427471, 489342, 557906, 633285, 716040, 806754

Offset: 0

Author

Clark Kimberling, Apr 28 2012

Keywords

• nonn

Comments

a(n)+A211923(n)=n^4.

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, 40]] (* A211920 *)
(* Peter J. C. Moses, Apr 13 2012 *)