Sum of first n terms of A(x)^n is A087457(n) for n>=1.

Terms

a(0) =1a(1) =2a(2) =4a(3) =9a(4) =23a(5) =67a(6) =220a(7) =795a(8) =3086a(9) =12633a(10) =53844a(11) =236833a(12) =1068313a(13) =4919512a(14) =23047579a(15) =109563206a(16) =527401808a(17) =2566472416a(18) =12608536729a(19) =62465984781a(20) =311796289951