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

Terms

a(0) =1a(1) =1a(2) =3a(3) =7a(4) =19a(5) =51a(6) =143a(7) =407a(8) =1179a(9) =3451a(10) =10183a(11) =30207a(12) =89939a(13) =268451a(14) =802623a(15) =2402407a(16) =7196299a(17) =21567051a(18) =64657463a(19) =193885007a(20) =581480259a(21) =1744091251a(22) =5231574703a(23) =15693326007a(24) =47077181819a(25) =141225953051a(26) =423666674343