A212132 Number of (w,x,y,z) with all terms in {1,...,n} and w*x+y*z>=n^2.

0, 1, 11, 33, 76, 144, 262, 415, 655, 959, 1377, 1886, 2610, 3396, 4465, 5689, 7169, 8883, 11042, 13334, 16240, 19355, 23003, 27059, 31892, 36952, 42878, 49384, 56659, 64471, 73683, 83042, 93938, 105470, 118114, 131855, 147087, 162883

Offset

0,3

Comments

A212132(n)+A212111(n)=n^4. For a guide to related sequences, see A211795.

Links

Table of n, a(n) for n=0..37.

Mathematica

t = Compile[{{n, _Integer}}, Module[{s = 0},
(Do[If[w*x + y*z >= n^2, s = s + 1],
{w, 1, #}, {x, 1, #}, {y, 1, #}, {z, 1, #}] &[n]; s)]];
Map[t[#] &, Range[0, 40]]  (* A212132 *)
(* Peter J. C. Moses, Apr 13 2012 *)

Crossrefs

Cf. A211795.

Sequence in context: A080859 A063036 A163673 * A027025 A366135 A120354

Adjacent sequences: A212129 A212130 A212131 * A212133 A212134 A212135

Keyword

nonn

Author

Clark Kimberling, May 07 2012

Status

approved