a(0) = 1; thereafter a(2*n + 1) = 3^n, a(2*n + 2) = 2 * 3^n.

Terms

a(0) =1a(1) =1a(2) =2a(3) =3a(4) =6a(5) =9a(6) =18a(7) =27a(8) =54a(9) =81a(10) =162a(11) =243a(12) =486a(13) =729a(14) =1458a(15) =2187a(16) =4374a(17) =6561a(18) =13122a(19) =19683a(20) =39366a(21) =59049a(22) =118098a(23) =177147a(24) =354294a(25) =531441a(26) =1062882a(27) =1594323a(28) =3188646a(29) =4782969