%I #8 Apr 06 2020 19:55:49
%S 0,0,1,0,0,1,1,1,0,0,1,0,1,1,1,0,0,1,0,0,1,0,1,1,1,0,0,0,0,1,0,0,1,1,
%T 1,1,0,1,1,0,0,1,0,1,0,0,0,0,1,0,1,1,1,0,1,1,1,0,1,1,1,0,0,1,0,0,0,0,
%U 1,0,0,0,1,0,0,1,1,1,1,0,1,1,1,1,0,1
%N Fixed point of the mapping 00->0010, 01->100, 10->011, starting with 00.
%C Conjecture: the number of letters (0's and 1's) in the n-th iterate of the mapping is given by A289177.
%H Clark Kimberling, <a href="/A289174/b289174.txt">Table of n, a(n) for n = 1..10000</a>
%e The first six iterates of the mapping:
%e 00
%e 0010
%e 0010011
%e 00100111001
%e 00100111001011100
%e 0010011100101110010010110
%t z = 11; (* number of iterates *)
%t s = {0, 0}; w[0] = StringJoin[Map[ToString, s]];
%t w[n_] := StringReplace[w[n - 1], {"00" -> "0010", "01" -> "100", "10" -> "011"}]
%t TableForm[Table[w[n], {n, 0, 10}]]
%t st = ToCharacterCode[w[z]] - 48 (* A289174 *)
%t Flatten[Position[st, 0]] (* A289175 *)
%t Flatten[Position[st, 1]] (* A289176 *)
%t Table[StringLength[w[n]], {n, 0, 20}] (* A289177 *)
%Y Cf. A289175, A289176, A289177.
%K nonn,easy
%O 1
%A _Clark Kimberling_, Jun 29 2017