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

Terms

a(0) =0a(1) =0a(2) =0a(3) =1a(4) =0a(5) =3a(6) =-4a(7) =5a(8) =-24a(9) =19a(10) =-76a(11) =133a(12) =-208a(13) =627a(14) =-852a(15) =2181a(16) =-4232a(17) =7443a(18) =-18012a(19) =30533a(20) =-66880a(21) =133875a(22) =-250724a(23) =547013a(24) =-1020152a(25) =2108435a(26) =-4245612a(27) =8217861a(28) =-17089968a(29) =33202291