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 A211427 #4 Apr 15 2012 21:22:09
%S A211427 1,5,9,21,33,37,49,53,65,77,81,85,113,117,121,133,153,157,169,173,185,
%T A211427 197,201,205,233,253,257,301,313,317,329,333,353,365,369,373,401,405,
%U A211427 409,421,433,437,449,453,465,477,481,485,537,573,593,605,617
%N A211427 Number of ordered triples (w,x,y) with all terms in {-n,...,0,...,n} and 3*w^2+x*y=0.
%C A211427 For a guide to related sequences, see A211422.
%t A211427 t[n_] := t[n] = Flatten[Table[3 w^2 + x*y, {w, -n, n}, {x, -n, n}, {y, -n, n}]]
%t A211427 c[n_] := Count[t[n], 0]
%t A211427 t = Table[c[n], {n, 0, 90}] (* A211427 *)
%t A211427 (t - 1)/4 (* integers *)
%Y A211427 Cf. A211422.
%K A211427 nonn
%O A211427 0,2
%A A211427 _Clark Kimberling_, Apr 10 2012