Number of ternary squarefree words of length n.

Terms

a(0) =1a(1) =3a(2) =6a(3) =12a(4) =18a(5) =30a(6) =42a(7) =60a(8) =78a(9) =108a(10) =144a(11) =204a(12) =264a(13) =342a(14) =456a(15) =618a(16) =798a(17) =1044a(18) =1392a(19) =1830a(20) =2388a(21) =3180a(22) =4146a(23) =5418a(24) =7032a(25) =9198a(26) =11892a(27) =15486a(28) =20220a(29) =26424