G.f. x^4*(2*x^2-1)/( (x^2-1)*(x^2+x-1)*(2*x^3-2*x^2+2*x-1) ).

Terms

a(0) =0a(1) =0a(2) =0a(3) =0a(4) =1a(5) =3a(6) =5a(7) =8a(8) =14a(9) =26a(10) =45a(11) =75a(12) =125a(13) =212a(14) =358a(15) =598a(16) =993a(17) =1651a(18) =2745a(19) =4552a(20) =7526a(21) =12426a(22) =20501a(23) =33787a(24) =55605a(25) =91404a(26) =150118a(27) =246350a(28) =403929a(29) =661763