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 A211428 #4 Apr 15 2012 21:22:21
%S A211428 1,5,9,21,25,29,49,53,65,77,81,85,105,109,113,125,137,141,161,165,169,
%T A211428 181,185,189,225,237,241,269,273,277,305,309,329,341,345,349,377,381,
%U A211428 385,397,409,413,433,437,441,453,457,461,497,517,545,557,561
%N A211428 Number of ordered triples (w,x,y) with all terms in {-n,...,0,...,n} and 2*w^2+3*x*y=0.
%C A211428 For a guide to related sequences, see A211422.
%t A211428 t[n_] := t[n] = Flatten[Table[2 w^2 + 3 x*y, {w, -n, n}, {x, -n, n}, {y, -n, n}]]
%t A211428 c[n_] := Count[t[n], 0]
%t A211428 t = Table[c[n], {n, 0, 70}] (* A211428 *)
%t A211428 (t - 1)/4 (* integers *)
%Y A211428 Cf. A211422.
%K A211428 nonn
%O A211428 0,2
%A A211428 _Clark Kimberling_, Apr 10 2012