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 A156256 #20 May 27 2021 09:52:54 %S A156256 0,2,1,0,1,0,2,2,0,1,2,1,0,2,2,1,0,1,0,2,1,0,1,2,2,0,1,0,2,1,0,1,0,2, %T A156256 2,1,0,1,2,0,1,0,2,1,0,1,0,2,2,0,1,2,1,0,1,0,2,2,1,0,2,2,0,1,2,2,0,1, %U A156256 0,2,1,0,1,2,0,1,0,1,2,2,0,1,0,2,1,0,1,2,2,0,1,2,1,0,2,2,1,0,1,2 %N A156256 Number of 1's separating successive 2's in the Kolakoski sequence A000002. %C A156256 After deleting 0's in this sequence it remains the bisection of Kolakoski sequence A000002(2n+1) n>=1 given by A100428. %C A156256 This is because A100428 gives the lengths of runs of 1's in Kolakoski sequence. - _Jean-Christophe Hervé_, Oct 14 2014 %C A156256 The Kolakovski sequence can be obtained back (except the initial 1) by the following substitution rules: insert 2 between two successive nonzero values and 0 -> 22, 1 -> 1, 2 -> 11. - _Jean-Christophe Hervé_, Oct 14 2014 %F A156256 a(n) = A078649(n+1)-A078649(n)-2. %e A156256 The Kolakoski sequence begins with 122112122122, thus this one begins 0, 2, 1, 0, 1, 0. - _Jean-Christophe Hervé_, Oct 14 2014 %Y A156256 Cf. A000002, A078649, A100428, A248806. %K A156256 nonn %O A156256 1,2 %A A156256 _Benoit Cloitre_, Feb 07 2009 %E A156256 Better name from _Jean-Christophe Hervé_, Oct 15 2014