A211633 Number of ordered triples (w,x,y) with all terms in {1,...,n} and w^2>2x^2+2y^2.

0, 0, 0, 8, 32, 80, 160, 264, 416, 624, 864, 1176, 1552, 2000, 2528, 3144, 3856, 4640, 5552, 6584, 7712, 8960, 10352, 11880, 13520, 15328, 17296, 19416, 21712, 24176, 26832, 29640, 32672, 35904, 39312, 42968, 46816, 50896, 55184, 59736

Offset

0,4

Comments

For a guide to related sequences, see A211422.

Links

Table of n, a(n) for n=0..39.

Mathematica

t = Compile[{{u, _Integer}},
   Module[{s = 0}, (Do[If[w^2 > 2 x^2 + 2 y^2,
         s = s + 1], {w, #}, {x, #}, {y, #}] &[
      Flatten[{Reverse[-#], #} &[Range[1, u]]]]; s)]];
Map[t[#] &, Range[0, 50]]  (* A211633 *)
%/8                        (* integers *)
(* Peter J. C. Moses, Apr 13 2012 *)

Crossrefs

Cf. A211422.

Sequence in context: A018842 A139098 A224543 * A130809 A333174 A372981

Adjacent sequences: A211630 A211631 A211632 * A211634 A211635 A211636

Keyword

nonn

Author

Clark Kimberling, Apr 17 2012

Status

approved