Expansion of g.f.: (1+x)/(1-9*x).

Terms

a(0) =1a(1) =10a(2) =90a(3) =810a(4) =7290a(5) =65610a(6) =590490a(7) =5314410a(8) =47829690a(9) =430467210a(10) =3874204890a(11) =34867844010a(12) =313810596090