G.f. A(x) satisfies A(x) = 1 + x^3 * A(x)^2 / (1 - x).

Terms

a(0) =1a(1) =0a(2) =0a(3) =1a(4) =1a(5) =1a(6) =3a(7) =5a(8) =7a(9) =14a(10) =26a(11) =43a(12) =79a(13) =148a(14) =264a(15) =483a(16) =903a(17) =1664a(18) =3080a(19) =5771a(20) =10795a(21) =20209a(22) =38059a(23) =71799a(24) =135569a(25) =256762a(26) =487310a(27) =925981a(28) =1762841a(29) =3361897