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

Terms

a(0) =1a(1) =2a(2) =6a(3) =14a(4) =38a(5) =94a(6) =246a(7) =622a(8) =1606a(9) =4094a(10) =10518a(11) =26894a(12) =68966a(13) =176542a(14) =452406a(15) =1158574a(16) =2968198a(17) =7602494a(18) =19475286a(19) =49885262a(20) =127786406a(21) =327327454a(22) =838473078a(23) =2147782894a(24) =5501675206a(25) =14092806782a(26) =36099507606a(27) =92470734734