Number of numbers that are ternary squarefree words of length n.

Terms

a(0) =1a(1) =3a(2) =4a(3) =8a(4) =12a(5) =20a(6) =28a(7) =40a(8) =52a(9) =72a(10) =96a(11) =136a(12) =176a(13) =228a(14) =304a(15) =412a(16) =532a(17) =696a(18) =928a(19) =1220a(20) =1592a(21) =2120a(22) =2764a(23) =3612a(24) =4688a(25) =6132a(26) =7928a(27) =10324a(28) =13480a(29) =17616