A211921 Number of (w,x,y,z) with all terms in {1,...,n} and 2w*x<=3*y*z.

0, 1, 11, 58, 176, 407, 840, 1536, 2591, 4133, 6268, 9119, 12895, 17684, 23706, 31201, 40315, 51239, 64352, 79770, 97829, 118795, 142947, 170548, 202114, 237757, 277915, 323080, 373489, 429449, 491670, 560274, 635851, 718858, 809692

Offset: 0

Author

Clark Kimberling, Apr 28 2012

Keywords

• nonn

Comments

a(n)+A211922(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]] (* A211921 *)
(* Peter J. C. Moses, Apr 13 2012 *)