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

Terms

a(0) =0a(1) =1a(2) =1a(3) =10a(4) =21a(5) =121a(6) =340a(7) =1561a(8) =5061a(9) =20890a(10) =72721a(11) =285121a(12) =1028160a(13) =3931201a(14) =14425201a(15) =54480250a(16) =201635301a(17) =756931801a(18) =2813339860a(19) =10529812921a(20) =39218508021a(21) =146573045290a(22) =546474598561