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

Terms

a(0) =1a(1) =1a(2) =2a(3) =4a(4) =9a(5) =20a(6) =47a(7) =111a(8) =270a(9) =663a(10) =1656a(11) =4174a(12) =10636a(13) =27308a(14) =70651a(15) =183902a(16) =481436a(17) =1266515a(18) =3346793a(19) =8879116a(20) =23642034a(21) =63156917a(22) =169222939a(23) =454660940a(24) =1224650739a(25) =3306338583a(26) =8945780742a(27) =24252558183a(28) =65872671839a(29) =179228552638