Aperiodic Necklaces
An aperiodic necklace of length n is an equivalence class of size n, i.e., no two distinct rotations of a necklace from such class are equal.
According to Moreau's necklace-counting function, there are
different k-ary aperiodic necklaces of length n, where μ is the Möbius function.
Each aperiodic necklace contains a single Lyndon word so that Lyndon words form representatives of aperiodic necklaces.
Read more about this topic: Necklace (combinatorics)