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A287455
Start with 0 and repeatedly substitute 0->012, 1->201, 2->210.
4
0, 1, 2, 2, 0, 1, 2, 1, 0, 2, 1, 0, 0, 1, 2, 2, 0, 1, 2, 1, 0, 2, 0, 1, 0, 1, 2, 2, 1, 0, 2, 0, 1, 0, 1, 2, 0, 1, 2, 2, 0, 1, 2, 1, 0, 2, 1, 0, 0, 1, 2, 2, 0, 1, 2, 1, 0, 2, 0, 1, 0, 1, 2, 2, 1, 0, 0, 1, 2, 2, 0, 1, 0, 1, 2, 2, 0, 1, 2, 1, 0, 2, 1, 0, 2, 0
OFFSET
1,3
COMMENTS
This is the fixed point of the morphism 0->012, 1->201, 2->210 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.
See A287385 for a guide to related sequences.
EXAMPLE
First three iterations of the morphism: 012, 012201210, 012201210210012201210201012.
MATHEMATICA
s = Nest[Flatten[# /. {0->{0, 1, 2}, 1->{2, 0, 1}, 2->{2, 1, 0}}] &, {0}, 9]; (*A287455*)
Flatten[Position[s, 0]]; (*A287456*)
Flatten[Position[s, 1]]; (*A287457*)
Flatten[Position[s, 2]]; (*A287458*)
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Clark Kimberling, May 30 2017
STATUS
approved