This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A211426 #4 Apr 15 2012 14:18:09
%S A211426 1,5,17,21,33,37,49,53,73,93,105,109,121,125,137,141,161,165,201,205,
%T A211426 217,221,233,237,257,285,297,317,329,333,345,349,393,397,409,413,449,
%U A211426 453,465,469,489,493,505,509,521,541,553,557,577,613,673,677
%N A211426 Number of ordered triples (w,x,y) with all terms in {-n,...,0,...,n} and 2*w^2+x*y=0.
%C A211426 For a guide to related sequences, see A211422.
%t A211426 t[n_] := t[n] = Flatten[Table[2 w^2 + x*y, {w, -n, n}, {x, -n, n}, {y, -n, n}]]
%t A211426 c[n_] := Count[t[n], 0]
%t A211426 t = Table[c[n], {n, 0, 70}] (* A211426 *)
%t A211426 (t - 1)/4 (* integers *)
%Y A211426 Cf. A211422.
%K A211426 nonn
%O A211426 0,2
%A A211426 _Clark Kimberling_, Apr 10 2012