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 A190671 #13 Apr 21 2018 08:31:46
%S A190671 1,4,5,8,9,12,13,15,16,19,20,23,24,27,30,31,34,35,38,39,42,45,46,49,
%T A190671 50,53,54,56,57,60,61,64,65,68,69,71,72,75,76,79,80,83,86,87,90,91,94,
%U A190671 95,98,101,102,105,106,109,110,112,113,116,117,120,121,124,125,127,128,131,132,135,136,139,142,143,146,147,150
%N A190671 Positions of 1 in A190669; complement of A190670.
%C A190671 See A190669.
%H A190671 G. C. Greubel, <a href="/A190671/b190671.txt">Table of n, a(n) for n = 1..10000</a>
%t A190671 r = Sqrt[3]; b = 2; c = 0;
%t A190671 f[n_] := Floor[(b*n + c)*r] - b*Floor[n*r] - Floor[c*r];
%t A190671 t = Table[f[n], {n, 1, 200}] (* A190669 *)
%t A190671 Flatten[Position[t, 0]] (* A190670 *)
%t A190671 Flatten[Position[t, 1]] (* A190671 *)
%Y A190671 Cf. A190669, A190670.
%K A190671 nonn
%O A190671 1,2
%A A190671 _Clark Kimberling_, May 16 2011