Expansion of (1+3*x)/(1-2*x-7*x^2).

Terms

a(0) =1a(1) =5a(2) =17a(3) =69a(4) =257a(5) =997a(6) =3793a(7) =14565a(8) =55681a(9) =213317a(10) =816401a(11) =3126021a(12) =11966849a(13) =45815845a(14) =175399633a(15) =671510181a(16) =2570817793a(17) =9842206853a(18) =37680138257a(19) =144255724485a(20) =552272416769