login
A308186
Fixed point (beginning with a) of the morphism a -> abab, b -> b, over the alphabet {a,b} = {1,2}.
4
1, 2, 1, 2, 2, 1, 2, 1, 2, 2, 2, 1, 2, 1, 2, 2, 1, 2, 1, 2, 2, 2, 2, 1, 2, 1, 2, 2, 1, 2, 1, 2, 2, 2, 1, 2, 1, 2, 2, 1, 2, 1, 2, 2, 2, 2, 2, 1, 2, 1, 2, 2, 1, 2, 1, 2, 2, 2, 1, 2, 1, 2, 2, 1, 2, 1, 2, 2, 2, 2, 1, 2, 1, 2, 2, 1, 2, 1, 2, 2, 2, 1, 2, 1, 2, 2, 1, 2, 1, 2, 2, 2, 2, 2, 2, 1, 2, 1, 2, 2, 1, 2, 1, 2, 2, 2, 1
OFFSET
1,2
COMMENTS
It seems likely that this is essentially the same sequence as A288932 without its leading 0, but the two definitions are so different that it is worth having both versions.
LINKS
M. Bucci, A. De Luca, A. Glen, L. Q. Zamboni, A connection between palindromic and factor complexity using return words, arXiv:0802.1332 [math.CO], 2008. See Section 4.
A. Glen, J. Justin, S. Widmer, L. Q. Zamboni, Palindromic richness, arXiv:0801.1656 [math.CO], 2008.
MAPLE
f:= 'f':
f(1):= (1, 2, 1, 2):
f(2):= 2:
A:= [1]:
for i from 1 to 9 do A:= map(f, A) od:
A; # Robert Israel, Jun 05 2019
MATHEMATICA
Nest[Flatten[ReplaceAll[#, 1->{1, 2, 1, 2}]]&, {1}, 6] (* Paolo Xausa, Nov 08 2023 *)
CROSSREFS
Sequence in context: A180227 A001468 A014675 * A107362 A166332 A022303
KEYWORD
nonn
AUTHOR
N. J. A. Sloane, Jun 05 2019
STATUS
approved