A005678 A squarefree ternary sequence. (Formerly M0134)

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, 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, 1, 2, 1, 3, 2, 1, 2, 3, 1, 3, 2, 3, 1, 2, 1, 3, 2, 1, 2

Offset

1,2

Comments

Rules: 1 -> 1213, 2 -> 2123, 3 preceded by 1 -> 2313, 3 preceded by 2 -> 1323. - Sean A. Irvine, Nov 08 2020

References

G. Siebert, personal communication.

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

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

Links

Table of n, a(n) for n=1..87.

J. Berstel, Axel Thue's papers on repetitions in words: a translation, 1994.

G. Siebert, Letter to N. J. A. Sloane, Sept. 1977

Crossrefs

Sequence in context: A153359 A240474 A023510 * A296976 A182321 A285731

Adjacent sequences: A005675 A005676 A005677 * A005679 A005680 A005681

Keyword

nonn

Author

N. J. A. Sloane

Extensions

More terms from Sean A. Irvine, Nov 08 2020

Status

approved