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 A211438 #7 Apr 18 2012 12:12:54
%S A211438 1,3,13,19,39,49,79,93,133,151,201,223,283,309,379,409,489,523,613,
%T A211438 651,751,793,903,949,1069,1119,1249,1303,1443,1501,1651,1713,1873,
%U A211438 1939,2109,2179,2359,2433,2623,2701,2901,2983,3193,3279,3499,3589
%N A211438 Number of ordered triples (w,x,y) with all terms in {-n,...,0,...,n} and w+2x+2y=0.
%C A211438 For a guide to related sequences, see A211422.
%F A211438 Conjecture: a(n) = (5+3*(-1)^n+2*(7+3*(-1)^n)*n+14*n^2)/8. G.f.: (1+2*x+8*x^2+2*x^3+x^4)/((1-x)^3*(1+x)^2). [_Colin Barker_, Apr 18 2012]
%t A211438 t[n_] := t[n] = Flatten[Table[w + 2 x + 2 y, {w, -n, n}, {x, -n, n}, {y, -n, n}]]
%t A211438 c[n_] := Count[t[n], 0]
%t A211438 t = Table[c[n], {n, 0, 70}] (* A211438 *)
%t A211438 (t - 1)/2 (* A118277 *)
%Y A211438 Cf. A211422.
%K A211438 nonn,easy
%O A211438 0,2
%A A211438 _Clark Kimberling_, Apr 11 2012