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

Terms

a(0) =1a(1) =2a(2) =3a(3) =6a(4) =9a(5) =18a(6) =27a(7) =54a(8) =81a(9) =162a(10) =243a(11) =486a(12) =729a(13) =1458a(14) =2187a(15) =4374a(16) =6561a(17) =13122a(18) =19683a(19) =39366a(20) =59049a(21) =118098a(22) =177147a(23) =354294a(24) =531441a(25) =1062882a(26) =1594323a(27) =3188646a(28) =4782969a(29) =9565938