a(n) = 5*a(n-1) + 4*a(n-2), with a(0) = 4, a(1) = 4.

Terms

a(0) =0a(1) =4a(2) =20a(3) =116a(4) =660a(5) =3764a(6) =21460a(7) =122356a(8) =697620a(9) =3977524a(10) =22678100a(11) =129300596a(12) =737215380a(13) =4203279284a(14) =23965257940a(15) =136639406836a(16) =779058065940