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 A190158 #11 Dec 29 2017 18:13:46
%S A190158 3,4,8,12,16,20,21,25,29,33,37,38,41,42,46,50,54,55,58,59,63,67,71,72,
%T A190158 75,76,80,84,88,92,93,97,101,105,109,110,113,114,118,122,126,127,130,
%U A190158 131,135,139,143,144,147,148,152,156,160,164,165,169,173,177,181,182,185,186,190,194,198,199,202,203,207,211,215,216,219,220
%N A190158 Positions of 2 in A189463.
%C A190158 See A189463.
%H A190158 G. C. Greubel, <a href="/A190158/b190158.txt">Table of n, a(n) for n = 1..5000</a>
%t A190158 r = 5^(1/2);
%t A190158 f[n_] := Floor[3 n*r] - 3*Floor[n*r];
%t A190158 t = Table[f[n], {n, 1, 220}] (* A189463 *)
%t A190158 Flatten[Position[t, 0]] (* A189464 *)
%t A190158 Flatten[Position[t, 1]] (* A189465 *)
%t A190158 Flatten[Position[t, 2]] (* A190158 *)
%Y A190158 Cf. A189463, A189464, A189465.
%K A190158 nonn
%O A190158 1,1
%A A190158 _Clark Kimberling_, May 22 2011