Primitive Words and Lyndon Words in Automatic and Linearly Recurrent   Sequences
  We investigate questions related to the presence of primitive words and Lyndon words in automatic and linearly recurrent sequences. We show that the Lyndon factorization of a k-automatic sequence is itself k-automatic. We also show that the function counting the number of primitive factors (resp., Lyndon factors) of length n in a k-automatic sequence is k-regular. Finally, we show that the number of Lyndon factors of a linearly recurrent sequence is bounded. 
Daniel Goc, Kalle Saari, Jeffrey Shallit
cs.FL math.CO