Expansion of g.f. (1-7*x)/(1-9*x).

Terms

a(0) =1a(1) =2a(2) =18a(3) =162a(4) =1458a(5) =13122a(6) =118098a(7) =1062882a(8) =9565938a(9) =86093442a(10) =774840978a(11) =6973568802a(12) =62762119218a(13) =564859072962