Set partitions up to rotations.

Terms

a(0) =1a(1) =1a(2) =2a(3) =3a(4) =7a(5) =12a(6) =43a(7) =127a(8) =544a(9) =2361a(10) =11703a(11) =61690a(12) =351773a(13) =2126497a(14) =13639372a(15) =92197523a(16) =655035769a(17) =4874404108a(18) =37893370473a(19) =306986431847