A005678 - OEIS

%I M0134 #21 Nov 09 2020 00:00:36

%S 1,2,1,3,2,1,2,3,1,2,1,3,2,3,1,3,2,1,2,3,1,2,1,3,2,1,2,3,1,3,2,3,1,2,

%T 1,3,2,1,2,3,1,2,1,3,2,3,1,3,2,1,2,3,1,3,2,3,1,2,1,3,2,3,1,3,2,1,2,3,

%U 1,2,1,3,2,1,2,3,1,3,2,3,1,2,1,3,2,1,2

%N A squarefree ternary sequence.

%C Rules: 1 -> 1213, 2 -> 2123, 3 preceded by 1 -> 2313, 3 preceded by 2 -> 1323. - _Sean A. Irvine_, Nov 08 2020

%D G. Siebert, personal communication.

%D N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).

%D A. Thue. Über unendliche Zeichenreihen, Norske Vid. Selsk. Skr. I. Mat. Nat. Kl. Christiania, No. 7 (1906), 1-22. See p. 14.

%H J. Berstel, <a href="http://www-igm.univ-mlv.fr/~berstel/Articles/1994ThueTranslation.pdf">Axel Thue's papers on repetitions in words: a translation</a>, 1994.

%H G. Siebert, <a href="/A001285/a001285_1.pdf">Letter to N. J. A. Sloane, Sept. 1977</a>

%K nonn

%O 1,2

%A _N. J. A. Sloane_

%E More terms from _Sean A. Irvine_, Nov 08 2020