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

Terms

a(0) =1a(1) =4a(2) =15a(3) =66a(4) =277a(5) =1176a(6) =4979a(7) =21094a(8) =89353a(9) =378508a(10) =1603383a(11) =6792042a(12) =28771549a(13) =121878240a(14) =516284507a(15) =2187016270a(16) =9264349585a(17) =39244414612a(18) =166242008031a(19) =704212446738