Floor[(80/81)*10^n].

Terms

a(0) =9a(1) =98a(2) =987a(3) =9876a(4) =98765a(5) =987654a(6) =9876543a(7) =98765432a(8) =987654320a(9) =9876543209a(10) =98765432098a(11) =987654320987