Number of aperiodic cycle necklaces with n vertices.

Terms

a(0) =1a(1) =0a(2) =0a(3) =0a(4) =2a(5) =7a(6) =51a(7) =300a(8) =2238a(9) =18028a(10) =164945a(11) =1662067a(12) =18423138a(13) =222380433a(14) =2905942904a(15) =40864642560a(16) =615376173176