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 A211439 #7 May 15 2017 10:58:20
%S A211439 1,3,5,19,25,31,59,69,79,121,135,149,205,223,241,311,333,355,439,465,
%T A211439 491,589,619,649,761,795,829,955,993,1031,1171,1213,1255,1409,1455,
%U A211439 1501,1669,1719,1769,1951,2005,2059,2255,2313,2371,2581,2643,2705
%N A211439 Number of ordered triples (w,x,y) with all terms in {-n,...,0,...,n} and w+3x+3y=0.
%C A211439 For a guide to related sequences, see A211422.
%F A211439 Conjectures from _Colin Barker_, May 15 2017: (Start)
%F A211439 G.f.: (1 + 2*x + 2*x^2 + 12*x^3 + 2*x^4 + 2*x^5 + x^6) / ((1 - x)^3*(1 + x + x^2)^2).
%F A211439 a(n) = a(n-1) + 2*a(n-3) - 2*a(n-4) - a(n-6) + a(n-7) for n>6.
%F A211439 (End)
%t A211439 t[n_] := t[n] = Flatten[Table[w + 3 x + 3 y, {w, -n, n}, {x, -n, n}, {y, -n, n}]]
%t A211439 c[n_] := Count[t[n], 0]
%t A211439 t = Table[c[n], {n, 0, 70}] (* A211439 *)
%t A211439 (t - 1)/2 (* integers *)
%Y A211439 Cf. A211422.
%K A211439 nonn
%O A211439 0,2
%A A211439 _Clark Kimberling_, Apr 11 2012