Expansion of (1-7x)/(1-10x).

Terms

a(0) =1a(1) =3a(2) =30a(3) =300a(4) =3000a(5) =30000a(6) =300000a(7) =3000000a(8) =30000000a(9) =300000000a(10) =3000000000a(11) =30000000000a(12) =300000000000