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 A189728 #7 May 25 2017 17:53:34
%S A189728 1,6,9,12,15,16,21,24,25,30,33,34,39,42,43,46,51,54,57,60,61,66,69,70,
%T A189728 73,78,81,84,87,88,93,96,97,100,105,108,111,114,115,120,123,124,127,
%U A189728 132,135,136,141,144,147,150,151,156,159,160,165,168,169,174,177,178,181,186,189,192,195,196,201,204,205,208,213,216,217,222,225
%N A189728 Positions of 0 in A189727; complement of A189729.
%C A189728 See A189727.
%C A189728 This sequence also gives the positions of 0 in the fixed point of the morphism 0->012, 1->210, 2->120. Moreover, a(n) - a(n-1) is in {1,3,5} for n >= 1; also, 3n - a(n) is in {0, 2} for n >= 1. The first 20 numbers 3n - a(n) are 2, 0, 0, 0, 0, 2, 0, 0, 2, 0, 0, 2, 0, 0, 2, 2, 0, 0, 0, 0, with 2 in positions given by A189728. - _Clark Kimberling_, May 25 2017
%H A189728 Clark Kimberling, <a href="/A189728/b189728.txt">Table of n, a(n) for n = 1..10000</a>
%t A189728 (See A189727 and A287401.)
%Y A189728 Cf. A189727, A189729, A189730, A287401.
%K A189728 nonn
%O A189728 1,2
%A A189728 _Clark Kimberling_, Apr 26 2011