a(n) = 3*a(n-2) for n > 2; a(1) = 4, a(2) = 3.

Terms

a(0) =4a(1) =3a(2) =12a(3) =9a(4) =36a(5) =27a(6) =108a(7) =81a(8) =324a(9) =243a(10) =972a(11) =729a(12) =2916a(13) =2187a(14) =8748a(15) =6561a(16) =26244a(17) =19683a(18) =78732a(19) =59049a(20) =236196a(21) =177147a(22) =708588a(23) =531441a(24) =2125764a(25) =1594323a(26) =6377292a(27) =4782969a(28) =19131876a(29) =14348907