A212810 Iterate the morphism 1->122, 2->1112 starting with 1.

1, 2, 2, 1, 1, 1, 2, 1, 1, 1, 2, 1, 2, 2, 1, 2, 2, 1, 2, 2, 1, 1, 1, 2, 1, 2, 2, 1, 2, 2, 1, 2, 2, 1, 1, 1, 2, 1, 2, 2, 1, 1, 1, 2, 1, 1, 1, 2, 1, 2, 2, 1, 1, 1, 2, 1, 1, 1, 2, 1, 2, 2, 1, 1, 1, 2, 1, 1, 1, 2, 1, 2, 2, 1, 2, 2, 1, 2, 2, 1, 1, 1, 2, 1, 2

Offset

1,2

Comments

This is an example of an infinite binary sequence in which no four blocks occur consecutively which are permutations of each other.

Links

N. J. A. Sloane, Table of n, a(n) for n = 1..1531

F. M. Dekking, Strongly nonrepetitive sequences and progression-free sets, J. Combin. Theory Ser. A 27 (1979), no. 2, 181--185. MR0542527 (81b:05027).

Example

1 -> 122 -> 122 1112 1112 -> ...

Crossrefs

Cf. A212811.

Sequence in context: A278514 A243840 A117898 * A072344 A140500 A156054

Adjacent sequences: A212807 A212808 A212809 * A212811 A212812 A212813

Keyword

nonn

Author

N. J. A. Sloane, May 29 2012

Status

approved