A211631 - OEIS

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A211631

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

0, 0, 8, 40, 104, 208, 384, 624, 952, 1384, 1920, 2584, 3368, 4304, 5416, 6696, 8160, 9808, 11680, 13784, 16120, 18696, 21552, 24672, 28064, 31752, 35768, 40128, 44808, 49816, 55200, 60952, 67112, 73664, 80624, 88032, 95848, 104120

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OFFSET

0,3

COMMENTS

For a guide to related sequences, see A211422.

LINKS

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

MATHEMATICA

t = Compile[{{u, _Integer}},

Module[{s = 0}, (Do[If[w^2 > x^2 + y^2,

s = s + 1], {w, #}, {x, #}, {y, #}] &[

Flatten[{Reverse[-#], #} &[Range[1, u]]]]; s)]];

Map[t[#] &, Range[0, 50]] (* A211631 *)

%/8 (* integers *)

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

CROSSREFS

Cf. A211422.

Sequence in context: A305075 A069083 A014642 * A279273 A143943 A135796

Adjacent sequences: A211628 A211629 A211630 * A211632 A211633 A211634

KEYWORD

nonn

AUTHOR

Clark Kimberling, Apr 17 2012

STATUS

approved