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

Terms

a(0) =1a(1) =2a(2) =4a(3) =8a(4) =18a(5) =40a(6) =88a(7) =194a(8) =428a(9) =944a(10) =2082a(11) =4592a(12) =10128a(13) =22338a(14) =49268a(15) =108664a(16) =239666a(17) =528600a(18) =1165864a(19) =2571394a(20) =5671388a(21) =12508640a(22) =27588674a(23) =60848736a(24) =134206112a(25) =296000898a(26) =652850532a(27) =1439907176a(28) =3175815250a(29) =7004481032