a(0)=1, a(1)=9, a(n) = 72*a(n-2) - a(n-1).

Terms

a(0) =1a(1) =9a(2) =63a(3) =585a(4) =3951a(5) =38169a(6) =246303a(7) =2501865a(8) =15231951a(9) =164902329a(10) =931798143a(11) =10941169545a(12) =56148296751a(13) =731615910489