a(n) = 3^n*Fibonacci(n).

Terms

a(0) =0a(1) =3a(2) =9a(3) =54a(4) =243a(5) =1215a(6) =5832a(7) =28431a(8) =137781a(9) =669222a(10) =3247695a(11) =15766083a(12) =76527504a(13) =371477259a(14) =1803179313a(15) =8752833270a(16) =42487113627a(17) =206236840311