Consider the Post tag system described in A284116 (but adapted to the alphabet {1,2}); sequence lists the words that belong to cycles.

A289674

Consider the Post tag system described in A284116 (but adapted to the alphabet {1,2}); sequence lists the words that belong to cycles.

Terms

    a(0) =21211a(1) =112212a(2) =21211221211a(3) =112212112212a(4) =221222121111

External references