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 A227939 #13 Oct 09 2013 06:13:18
%S A227939 1,3,4,9,11,12,16,19,25,27,33,36,43,44,48,49,51,57,59,64,67,73,75,76,
%T A227939 81,83,89,99,100,107,108,121,123,129,131,132,139,144,147,163,169,171,
%U A227939 172,176,177,179,187,192
%N A227939 Values of n such that the equation x^2 - 2*n*y^2 = n has integer solutions.
%H A227939 Vincenzo Librandi, <a href="/A227939/b227939.txt">Table of n, a(n) for n = 1..440</a>
%e A227939 59 appears in the sequence because the equation x^2 - 118*y^2 = 59 has integer solutions.
%t A227939 Select[Range[200],Length[FullSimplify[Solve[x^2-2*#*y^2==#,{x,y},Integers]/.C[1]->1]]>0&] (* _Vaclav Kotesovec_, Oct 08 2013 *)
%Y A227939 Cf. A172000, A229848
%K A227939 nonn
%O A227939 1,2
%A A227939 _Colin Barker_, Oct 07 2013