Number of periodic necklaces with n beads of 3 colors.

Terms

a(0) =0a(1) =0a(2) =3a(3) =3a(4) =6a(5) =3a(6) =14a(7) =3a(8) =24a(9) =11a(10) =54a(11) =3a(12) =148a(13) =3a(14) =318a(15) =59a(16) =834a(17) =3a(18) =2314a(19) =3a(20) =5952a(21) =323a(22) =16110a(23) =3a(24) =45178a(25) =51a(26) =122646a(27) =2195a(28) =341820a(29) =3