a(n) = 3*a(n-2) for n > 2; a(1) = 1, a(2) = 6.

Terms

a(0) =1a(1) =6a(2) =3a(3) =18a(4) =9a(5) =54a(6) =27a(7) =162a(8) =81a(9) =486a(10) =243a(11) =1458a(12) =729a(13) =4374a(14) =2187a(15) =13122a(16) =6561a(17) =39366a(18) =19683a(19) =118098a(20) =59049a(21) =354294a(22) =177147a(23) =1062882a(24) =531441a(25) =3188646a(26) =1594323a(27) =9565938a(28) =4782969a(29) =28697814