Number of ternary squarefree necklaces.

Terms

a(0) =1a(1) =3a(2) =6a(3) =6a(4) =12a(5) =0a(6) =18a(7) =0a(8) =24a(9) =0a(10) =0a(11) =66a(12) =72a(13) =78a(14) =0a(15) =30a(16) =48a(17) =0a(18) =252a(19) =228a(20) =300a(21) =42a(22) =462a(23) =690a(24) =720a(25) =750a(26) =702a(27) =810a(28) =1260a(29) =2088