A211917 Number of (w,x,y,z) with all terms in {1,...,n} and w*x<3*y*z.

0, 1, 15, 67, 210, 507, 1029, 1904, 3225, 5123, 7785, 11368, 16023, 22035, 29572, 38867, 50233, 63931, 80180, 99459, 121947, 148024, 178141, 212635, 251805, 296268, 346348, 402462, 465175, 534990, 612224, 697732, 791813, 895043

Offset

0,3

Comments

a(n)+A211919(n)=n^4.

See A211795 for a guide to related sequences.

Links

Table of n, a(n) for n=0..33.

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]] (* A211917 *)
(* Peter J. C. Moses, Apr 13 2012 *)

Crossrefs

Cf. A211795.

Sequence in context: A211787 A265141 A336624 * A015876 A201126 A085474

Adjacent sequences: A211914 A211915 A211916 * A211918 A211919 A211920

Keyword

nonn

Author

Clark Kimberling, Apr 27 2012

Status

approved