Expansion of solution of functional equation.

Terms

a(0) =1a(1) =1a(2) =3a(3) =13a(4) =66a(5) =365a(6) =2132a(7) =12940a(8) =80804a(9) =515776a(10) =3350165a(11) =22071930a(12) =147141469a(13) =990714900a(14) =6727506071a(15) =46020535285a(16) =316837676938