Number of n-bead necklaces with beads of 2 colors and primitive period n, when turning over is allowed.

A001371

Number of n-bead necklaces with beads of 2 colors and primitive period n, when turning over is allowed.

Terms

    a(0) =1a(1) =2a(2) =1a(3) =2a(4) =3a(5) =6a(6) =8a(7) =16a(8) =24a(9) =42a(10) =69a(11) =124a(12) =208a(13) =378a(14) =668a(15) =1214a(16) =2220a(17) =4110a(18) =7630a(19) =14308a(20) =26931a(21) =50944a(22) =96782a(23) =184408a(24) =352450a(25) =675180a(26) =1296477a(27) =2493680a(28) =4805388a(29) =9272778

External references