A212055 Number of (w,x,y,z) with all terms in {1,...,n} and w*x<=y*z+2.

0, 1, 15, 62, 176, 395, 775, 1382, 2296, 3595, 5407, 7822, 10968, 14995, 20063, 26286, 33896, 43043, 53951, 66798, 81832, 99251, 119375, 142382, 168592, 198251, 231711, 269190, 311088, 357675, 409367, 466422, 529296, 598267, 673855

Offset

0,3

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]] (* A212055 *)
(* Peter J. C. Moses, Apr 13 2012 *)

Crossrefs

Cf. A211795.

Sequence in context: A157446 A220084 A240711 * A219296 A067572 A066584

Adjacent sequences: A212052 A212053 A212054 * A212056 A212057 A212058

Keyword

nonn

Author

Clark Kimberling, Apr 29 2012

Status

approved