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 A190490 #8 Jul 03 2017 02:09:23
%S A190490 2,7,9,12,14,19,21,24,26,31,33,36,38,41,43,48,50,53,55,60,62,65,67,70,
%T A190490 72,77,79,82,84,89,91,94,96,101,106,108,111,113,118,120,123,125,130,
%U A190490 132,135,137,140,142,147,149,152,154,159,161,164,166,171,176,178,181,183,188,190,193,195,200,202,205,207,210,212,217,219,222
%N A190490 Positions of 2 in A190487.
%H A190490 G. C. Greubel, <a href="/A190490/b190490.txt">Table of n, a(n) for n = 1..1000</a>
%t A190490 r = Sqrt[2]; b = 3; c = 0;
%t A190490 f[n_] := Floor[(b*n + c)*r] - b*Floor[n*r] - Floor[c*r];
%t A190490 t = Table[f[n], {n, 1, 200}] (* A190487 *)
%t A190490 Flatten[Position[t, 0]] (* A190488 *)
%t A190490 Flatten[Position[t, 1]] (* A190489 *)
%t A190490 Flatten[Position[t, 2]] (* A190490 *)
%Y A190490 Cf. A190487.
%K A190490 nonn
%O A190490 1,1
%A A190490 _Clark Kimberling_, May 11 2011