a(n) = 5*a(n-1) - 2*a(n-2), with a(0)=2, a(1)=9.

Terms

a(0) =2a(1) =9a(2) =41a(3) =187a(4) =853a(5) =3891a(6) =17749a(7) =80963a(8) =369317a(9) =1684659a(10) =7684661a(11) =35053987a(12) =159900613a(13) =729395091a(14) =3327174229a(15) =15177080963a(16) =69231056357a(17) =315801119859