a(n) = ceiling(a(n-1)*3/2) with a(1) = 1.

Terms

a(0) =1a(1) =2a(2) =3a(3) =5a(4) =8a(5) =12a(6) =18a(7) =27a(8) =41a(9) =62a(10) =93a(11) =140a(12) =210a(13) =315a(14) =473a(15) =710a(16) =1065a(17) =1598a(18) =2397a(19) =3596a(20) =5394a(21) =8091a(22) =12137a(23) =18206a(24) =27309a(25) =40964a(26) =61446a(27) =92169a(28) =138254a(29) =207381