A225188 Words u such that uu is a factor of the Thue-Morse word A001285.

1, 2, 12, 21, 121, 212, 1221, 2112, 122112, 211221, 12212112, 21121221, 122121121221, 211212212112, 1221211221121221, 2112122112212112, 122121122112122112212112, 211212211221211221121221, 12212112211212212112122112212112, 21121221122121121221211221121221, 122121122112122121121221122121121221211221121221, 211212211221211212212112211212212112122112212112

Offset: 1

Author

N. J. A. Sloane, May 05 2013

Keywords

• nonn

Comments

Consists of 1, 2, 121, 212 and their repeated images under the morphism 1 -> 12, 2 -> 21.

These are the square roots of the words in A225186.

Replacing {1,2} by {0,1} gives the words u such that uu is a factor of A010060.

Links

• James D. Currie and Narad Rampersad, Infinite words containing squares at every position, arXiv:0803.1189 [math.CO], 2008; or also, RAIRO-Theor. Inf. Appl. 44, 113-124 (2010).

Crossrefs

Cf. A001285, A020060, A225186.