Number of n-bead necklaces labeled with numbers 1..3 allowing reversal, with no adjacent beads differing by more than 1.

A208716

Number of n-bead necklaces labeled with numbers 1..3 allowing reversal, with no adjacent beads differing by more than 1.

Terms

    a(0) =3a(1) =5a(2) =7a(3) =12a(4) =18a(5) =34a(6) =56a(7) =111a(8) =207a(9) =427a(10) =859a(11) =1851a(12) =3930a(13) =8672a(14) =19092a(15) =42845a(16) =96243a(17) =218567a(18) =497183a(19) =1138084a(20) =2610226a(21) =6009662a(22) =13861968a(23) =32057868a(24) =74260243a(25) =172351415a(26) =400589343a(27) =932486879a(28) =2173368730a(29) =5071877864

External references