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

Terms

a(0) =0a(1) =3a(2) =3a(3) =7a(4) =9a(5) =18a(6) =24a(7) =47a(8) =63a(9) =123a(10) =165a(11) =322a(12) =432a(13) =843a(14) =1131a(15) =2207a(16) =2961a(17) =5778a(18) =7752a(19) =15127a(20) =20295a(21) =39603a(22) =53133a(23) =103682a(24) =139104a(25) =271443a(26) =364179a(27) =710647a(28) =953433a(29) =1860498