G.f. satisfies A(x) = 1/(1-x) + x^3*(1-x)*A(x)^5.

Terms

a(0) =1a(1) =1a(2) =1a(3) =2a(4) =5a(5) =11a(6) =26a(7) =71a(8) =197a(9) =540a(10) =1521a(11) =4401a(12) =12826a(13) =37597a(14) =111385a(15) =332861a(16) =1000181a(17) =3021071a(18) =9174308a(19) =27987989a(20) =85712801a(21) =263438881a(22) =812394661a(23) =2512807846a(24) =7793552386a(25) =24233089051a(26) =75526196851a(27) =235897169106a(28) =738271145577