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

Terms

a(0) =1a(1) =0a(2) =0a(3) =0a(4) =1a(5) =4a(6) =6a(7) =4a(8) =5a(9) =32a(10) =112a(11) =224a(12) =302a(13) =488a(14) =1564a(15) =4872a(16) =11034a(17) =19664a(18) =37128a(19) =95824a(20) =266659a(21) =635740a(22) =1306682a(23) =2706524a(24) =6503711a(25) =16794992a(26) =40634744a(27) =90066416a(28) =197648134a(29) =465436936