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%I #16 Nov 08 2023 11:17:17
%S 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,
%T 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,
%U 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
%N Fixed point (beginning with a) of the morphism a -> abab, b -> b, over the alphabet {a,b} = {1,2}.
%C 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.
%H Robert Israel, <a href="/A308186/b308186.txt">Table of n, a(n) for n = 1..10000</a>
%H M. Bucci, A. De Luca, A. Glen, L. Q. Zamboni, <a href="https://arxiv.org/abs/0802.1332">A connection between palindromic and factor complexity using return words</a>, arXiv:0802.1332 [math.CO], 2008. See Section 4.
%H A. Glen, J. Justin, S. Widmer, L. Q. Zamboni, <a href="https://arxiv.org/abs/0801.1656">Palindromic richness</a>, arXiv:0801.1656 [math.CO], 2008.
%p f:= 'f':
%p f(1):= (1,2,1,2):
%p f(2):= 2:
%p A:= [1]:
%p for i from 1 to 9 do A:= map(f,A) od:
%p A; # _Robert Israel_, Jun 05 2019
%t Nest[Flatten[ReplaceAll[#,1->{1,2,1,2}]]&,{1},6] (* _Paolo Xausa_, Nov 08 2023 *)
%Y Cf. A288932, A308185.
%K nonn
%O 1,2
%A _N. J. A. Sloane_, Jun 05 2019
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