A211918 Number of (w,x,y,z) with all terms in {1,...,n} and w*x>3*y*z.

0, 0, 1, 6, 32, 100, 219, 441, 797, 1312, 2061, 3107, 4451, 6248, 8526, 11336, 14823, 19090, 24122, 30164, 37253, 45501, 55091, 66154, 78663, 92979, 109170, 127281, 147629, 170403, 195536, 223509, 254329, 288192, 325385, 366061

Offset

0,4

Comments

a(n)+A211912(n)=n^4.

See A211795 for a guide to related sequences.

Links

Table of n, a(n) for n=0..35.

Mathematica

t = Compile[{{n, _Integer}}, Module[{s = 0},
(Do[If[w*x > 3 y*z, s = s + 1],
{w, 1, #}, {x, 1, #}, {y, 1, #}, {z, 1, #}] &[n]; s)]];
Map[t[#] &, Range[0, 40]] (* A211918 *)
(* Peter J. C. Moses, Apr 13 2012 *)

Crossrefs

Cf. A211795.

Sequence in context: A305291 A177082 A296196 * A288961 A090382 A360839

Adjacent sequences: A211915 A211916 A211917 * A211919 A211920 A211921

Keyword

nonn

Author

Clark Kimberling, Apr 27 2012

Status

approved