A word is said to be overlapfree if it has no subwords of the form xyxyx. A squarefree word is overlapfree, and an overlapfree word is cubefree. The numbers t(n) of binary overlapfree words of length n = 1, 2, ... are 2, 4, 6, 10, 14, 20, ... (OEIS A007777). t(n) satisfies p·n^1.155<=t(n)<=q·n^1.587 for some constants p and q (Restivo and Selemi 1985, Kobayashi 1988).

cubefree word | squarefree word | word