Number of n-bead necklace structures using a maximum of four different colored beads and no adjacent beads having the same color.

A309673

Number of n-bead necklace structures using a maximum of four different colored beads and no adjacent beads having the same color.

Terms

    a(0) =0a(1) =1a(2) =1a(3) =3a(4) =2a(5) =9a(6) =13a(7) =41a(8) =94a(9) =257a(10) =671a(11) =1881a(12) =5110a(13) =14301a(14) =39871a(15) =112281a(16) =316520a(17) =897297a(18) =2548819a(19) =7265383a(20) =20754748a(21) =59437181a(22) =170549237a(23) =490338539a(24) =1412147684a(25) =4073528481a(26) =11767897903a(27) =34042917197a(28) =98606864030a(29) =285960106473

External references