Expansion of (1+3*x)/(1-4*x+x^2).

Terms

a(0) =1a(1) =7a(2) =27a(3) =101a(4) =377a(5) =1407a(6) =5251a(7) =19597a(8) =73137a(9) =272951a(10) =1018667a(11) =3801717a(12) =14188201a(13) =52951087a(14) =197616147a(15) =737513501a(16) =2752437857a(17) =10272237927a(18) =38336513851a(19) =143073817477a(20) =533958756057