|
%I #14 Dec 01 2018 04:35:54
%S 1,2,2,1,1,1,2,1,1,1,2,1,2,2,1,2,2,1,2,2,1,1,1,2,1,2,2,1,2,2,1,2,2,1,
%T 1,1,2,1,2,2,1,1,1,2,1,1,1,2,1,2,2,1,1,1,2,1,1,1,2,1,2,2,1,1,1,2,1,1,
%U 1,2,1,2,2,1,2,2,1,2,2,1,1,1,2,1,2
%N Iterate the morphism 1->122, 2->1112 starting with 1.
%C This is an example of an infinite binary sequence in which no four blocks occur consecutively which are permutations of each other.
%H N. J. A. Sloane, <a href="/A212810/b212810.txt">Table of n, a(n) for n = 1..1531</a>
%H F. M. Dekking, <a href="https://doi.org/10.1016/0097-3165(79)90044-X">Strongly nonrepetitive sequences and progression-free sets</a>, J. Combin. Theory Ser. A 27 (1979), no. 2, 181--185. MR0542527 (81b:05027).
%e 1 -> 122 -> 122 1112 1112 -> ...
%Y Cf. A212811.
%K nonn
%O 1,2
%A _N. J. A. Sloane_, May 29 2012
|
