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

Terms

a(0) =1a(1) =2a(2) =10a(3) =34a(4) =134a(5) =498a(6) =1894a(7) =7138a(8) =26998a(9) =101970a(10) =385350a(11) =1455938a(12) =5501334a(13) =20786354a(14) =78540646a(15) =296762018a(16) =1121303222a(17) =4236795154a(18) =16008550278a(19) =60487618562a(20) =228549876182a(21) =863565901682