Number of n-bead necklaces of 3 colors allowing reversal, with no adjacent beads having the same color.

A208539

Number of n-bead necklaces of 3 colors allowing reversal, with no adjacent beads having the same color.

Terms

    a(0) =3a(1) =3a(2) =1a(3) =6a(4) =3a(5) =13a(6) =9a(7) =30a(8) =29a(9) =78a(10) =93a(11) =224a(12) =315a(13) =687a(14) =1095a(15) =2250a(16) =3855a(17) =7685a(18) =13797a(19) =27012a(20) =49939a(21) =96909a(22) =182361a(23) =352698a(24) =671091a(25) =1296858a(26) =2485533a(27) =4806078a(28) =9256395a(29) =17920860

External references