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 A211424 #13 Jun 25 2020 15:14:07
%S A211424 1,5,9,21,25,29,49,53,57,69,73,77,105,109,113,125,137,141,161,165,169,
%T A211424 181,185,189,217,229,233,261,265,269,297,301,313,325,329,333,369,373,
%U A211424 377,389,393,397,417,421,425,445,449,453,497,517,529,541,545
%N A211424 Number of ordered triples (w,x,y) with all terms in {-n,...,0,...,n} and w^2+3*x*y=0.
%C A211424 For a guide to related sequences, see A211422.
%H A211424 Brandon Crofts, <a href="/A211424/b211424.txt">Table of n, a(n) for n = 0..20000</a>
%H A211424 Brandon Crofts, <a href="/A211424/a211424.txt">Faster Mathematica code for A211424</a>
%t A211424 t[n_] := t[n] = Flatten[Table[w^2 + 3 x*y, {w, -n, n}, {x, -n, n}, {y, -n, n}]]
%t A211424 c[n_] := Count[t[n], 0]
%t A211424 t = Table[c[n], {n, 0, 70}] (* A211424 *)
%t A211424 (t - 1)/4 (* integers *)
%Y A211424 Cf. A211422.
%K A211424 nonn
%O A211424 0,2
%A A211424 _Clark Kimberling_, Apr 10 2012