Abstract
In a recent paper (8), Christol and al. introduce the following generalized Thue-Morse sequences over two letters a and b. Given a finite word u over {0,1}, the infinite word u has its i-th letter equal to a or b according to the number of occurrences of u in the binary expansion of i be even or odd.
Černý (7) has shown that these words do not contain any factor of the form (xy)nx, with n=2|u|.
We considerably strengthen this result, and prove that these words contain no cube exepted ap and bp, p≤n.
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Séébold, P. (1985). Generalized thue-morse sequences. In: Budach, L. (eds) Fundamentals of Computation Theory. FCT 1985. Lecture Notes in Computer Science, vol 199. Springer, Berlin, Heidelberg. https://doi.org/10.1007/BFb0028824
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DOI: https://doi.org/10.1007/BFb0028824
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