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Start with 0 and repeatedly substitute 0->012, 1->102, 2->201.
3

%I #9 Jun 01 2017 21:09:47

%S 0,1,2,1,0,2,2,0,1,1,0,2,0,1,2,2,0,1,2,0,1,0,1,2,1,0,2,1,0,2,0,1,2,2,

%T 0,1,0,1,2,1,0,2,2,0,1,2,0,1,0,1,2,1,0,2,2,0,1,0,1,2,1,0,2,0,1,2,1,0,

%U 2,2,0,1,1,0,2,0,1,2,2,0,1,1,0,2,0,1

%N Start with 0 and repeatedly substitute 0->012, 1->102, 2->201.

%C This is the fixed point of the morphism 0->012, 1->102, 2->201 starting with 0. Let u be the (nonperiodic) sequence of positions of 0, and likewise, v for 1 and w for 2; then u(n)/n -> 3, v(n)/n -> 3, w(n)/n -> 3.

%C See A287385 for a guide to related sequences.

%H Clark Kimberling, <a href="/A287524/b287524.txt">Table of n, a(n) for n = 1..10000</a>

%H <a href="/index/Fi#FIXEDPOINTS">Index entries for sequences that are fixed points of mappings</a>

%e First three iterations of the morphism: 012, 012102201, 012102201102012201201012102.

%t s = Nest[Flatten[# /. {0->{0, 1, 2}, 1->{1, 0, 2}, 2->{2, 0, 1}}] &, {0}, 9]; (*A287524*)

%t Flatten[Position[s, 0]]; (*A189724*)

%t Flatten[Position[s, 1]]; (*A287526*)

%t Flatten[Position[s, 2]]; (*A189634*)

%Y Cf. A189724, A287385, A287526, A189634.

%K nonn,easy

%O 1,3

%A _Clark Kimberling_, May 30 2017