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 A192591 #4 Mar 30 2012 18:57:35
%S A192591 1,3,11,19,131
%N A192591 Monotonic ordering of set S generated by these rules: if x and y are in S and x^2+y^2+1 is a prime, then x^2+y^2+1 is in S, and 1 is in S.
%C A192591 See the discussions at A192476 and A192580.
%t A192591 start = {1}; primes = Table[Prime[n], {n, 1, 40000}];
%t A192591 f[x_, y_] := If[MemberQ[primes, x^2 + y^2 + 1], x^2 + y^2 + 1]
%t A192591 b[x_] :=
%t A192591 Block[{w = x},
%t A192591 Select[Union[
%t A192591 Flatten[AppendTo[w,
%t A192591 Table[f[w[[i]], w[[j]]], {i, 1, Length[w]}, {j, 1, i}]]]], # <
%t A192591 200000 &]];
%t A192591 t = FixedPoint[b, start] (* A192591 *)
%Y A192591 Cf. A192476, A192580.
%K A192591 nonn,fini,full
%O A192591 1,2
%A A192591 _Clark Kimberling_, Jul 05 2011