a(1)=4, a(2)=3, a(n) = 4*a(n-1) + 3*a(n-2).

Terms

a(0) =4a(1) =3a(2) =24a(3) =105a(4) =492a(5) =2283a(6) =10608a(7) =49281a(8) =228948a(9) =1063635a(10) =4941384a(11) =22956441a(12) =106649916a(13) =495468987a(14) =2301825696a(15) =10693709745a(16) =49680316068a(17) =230802393507