G.f.: x^3*(2*x-1) / ((1-x)*(1-x-x^2)*(1-2*x^2)).

Terms

a(0) =0a(1) =0a(2) =0a(3) =-1a(4) =0a(5) =-2a(6) =1a(7) =-2a(8) =6a(9) =3a(10) =24a(11) =26a(12) =81a(13) =106a(14) =250a(15) =355a(16) =732a(17) =1086a(18) =2073a(19) =3158a(20) =5742a(21) =8899a(22) =15664a(23) =24562a(24) =42273a(25) =66834a(26) =113202a(27) =180035a(28) =301428a(29) =481462