%I #8 Jan 21 2018 09:35:55
%S 0,0,0,1,0,0,0,1,0,0,0,1,1,1,1,0,0,0,0,1,0,0,0,1,0,0,0,1,1,1,1,0,0,0,
%T 0,1,0,0,0,1,0,0,0,1,1,1,1,0,1,1,1,0,1,1,1,0,1,1,1,0,0,0,0,1,0,0,0,1,
%U 0,0,0,1,0,0,0,1,1,1,1,0,0,0,0,1,0,0,0,1,0,0,0,1,1,1,1,0,0,0,0,1,0
%N Image of 0 under repeated applications of the morphism 0 -> 0,0,0,1, 1 -> 1,1,1,0.
%p with(ListTools);
%p psi:=proc(S)
%p Flatten(subs( {0=[0,0,0,1], 1=[1,1,1,0]}, S));
%p end;
%p S:=[0];
%p for n from 1 to 6 do S:=psi(S): od:
%p S;
%t SubstitutionSystem[{0 -> {0, 0, 0, 1}, 1 -> {1, 1, 1, 0}}, {0}, 4] // Last (* _Jean-François Alcover_, Jan 21 2018 *)
%Y Suggested by A283317.
%K nonn
%O 1
%A _N. J. A. Sloane_, Mar 08 2017
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