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 A190670 #9 Apr 21 2018 06:46:46
%S A190670 2,3,6,7,10,11,14,17,18,21,22,25,26,28,29,32,33,36,37,40,41,43,44,47,
%T A190670 48,51,52,55,58,59,62,63,66,67,70,73,74,77,78,81,82,84,85,88,89,92,93,
%U A190670 96,97,99,100,103,104,107,108,111,114,115,118,119,122,123,126,129,130,133,134,137,138,140,141,144,145,148,149
%N A190670 Positions of 0 in A190669; complement of A190671.
%C A190670 See A190669.
%H A190670 G. C. Greubel, <a href="/A190670/b190670.txt">Table of n, a(n) for n = 1..10000</a>
%t A190670 r = Sqrt[3]; b = 2; c = 0;
%t A190670 f[n_] := Floor[(b*n + c)*r] - b*Floor[n*r] - Floor[c*r];
%t A190670 t = Table[f[n], {n, 1, 200}] (* A190669 *)
%t A190670 Flatten[Position[t, 0]] (* A190670 *)
%t A190670 Flatten[Position[t, 1]] (* A190671 *)
%Y A190670 Cf. A190669, A190671.
%K A190670 nonn
%O A190670 1,1
%A A190670 _Clark Kimberling_, May 16 2011