a(n) = floor(7^n/6^n).

Terms

a(0) =1a(1) =1a(2) =1a(3) =1a(4) =1a(5) =2a(6) =2a(7) =2a(8) =3a(9) =4a(10) =4a(11) =5a(12) =6a(13) =7a(14) =8a(15) =10a(16) =11a(17) =13a(18) =16a(19) =18a(20) =21a(21) =25a(22) =29a(23) =34a(24) =40a(25) =47a(26) =55a(27) =64a(28) =74a(29) =87