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

Terms

a(0) =1a(1) =3a(2) =7a(3) =19a(4) =47a(5) =123a(6) =311a(7) =803a(8) =2047a(9) =5259a(10) =13447a(11) =34483a(12) =88271a(13) =226203a(14) =579287a(15) =1484099a(16) =3801247a(17) =9737643a(18) =24942631a(19) =63893203a(20) =163663727a(21) =419236539a(22) =1073891447a(23) =2750837603a(24) =7046403391a(25) =18049753803a(26) =46235367367a(27) =118434382579a(28) =303375852047a(29) =777113382363