G.f. satisfies A(x) = 1 + x + x^2*A(x)^4.

Terms

a(0) =1a(1) =1a(2) =1a(3) =4a(4) =10a(5) =32a(6) =107a(7) =360a(8) =1270a(9) =4544a(10) =16537a(11) =61092a(12) =228084a(13) =860056a(14) =3269994a(15) =12521488a(16) =48250690a(17) =186959312a(18) =727989318a(19) =2847167632a(20) =11179394088a(21) =44053232012a(22) =174160578150a(23) =690576010820