A212056 Number of (w,x,y,z) with all terms in {1,...,n} and w*x>y*z+2.

0, 0, 1, 19, 80, 230, 521, 1019, 1800, 2966, 4593, 6819, 9768, 13566, 18353, 24339, 31640, 40478, 51025, 63523, 78168, 95230, 114881, 137459, 163184, 192374, 225265, 262251, 303568, 349606, 400633, 457099, 519280, 587654, 662481

Offset

0,4

Comments

a(n)+A212056(n)=n^4. See A211795 for a guide to related sequences.

Links

Table of n, a(n) for n=0..34.

Mathematica

t = Compile[{{n, _Integer}}, Module[{s = 0},
(Do[If[w*x > y*z + 2, s = s + 1],
{w, 1, #}, {x, 1, #}, {y, 1, #}, {z, 1, #}] &[n]; s)]];
Map[t[#] &, Range[0, 50]] (* A212056 *)
(* Peter J. C. Moses, Apr 13 2012 *)

Crossrefs

Cf. A211795.

Sequence in context: A050522 A366965 A172973 * A290224 A071633 A334086

Adjacent sequences: A212053 A212054 A212055 * A212057 A212058 A212059

Keyword

nonn

Author

Clark Kimberling, Apr 29 2012

Status

approved