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 A211425 #5 Apr 15 2012 14:17:43
%S A211425 1,5,13,17,33,37,45,49,65,77,85,89,113,117,125,129,153,157,173,177,
%T A211425 193,197,205,209,241,261,269,281,297,301,317,321,345,349,357,361,401,
%U A211425 405,413,417,441,445,453,457,473,485,493,497,537,565,589,593,609
%N A211425 Number of ordered triples (w,x,y) with all terms in {-n,...,0,...,n} and w^2+4*x*y=0.
%C A211425 For a guide to related sequences, see A211422.
%t A211425 t[n_] := t[n] = Flatten[Table[w^2 + 4 x*y, {w, -n, n}, {x, -n, n}, {y, -n, n}]]
%t A211425 c[n_] := Count[t[n], 0]
%t A211425 t = Table[c[n], {n, 0, 70}] (* A211425 *)
%t A211425 (t - 1)/4 (* integers *)
%Y A211425 Cf. A211422.
%K A211425 nonn
%O A211425 0,2
%A A211425 _Clark Kimberling_, Apr 10 2012