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

Terms

a(0) =1a(1) =1a(2) =5a(3) =20a(4) =90a(5) =440a(6) =2236a(7) =11720a(8) =62960a(9) =344690a(10) =1916170a(11) =10787762a(12) =61380770a(13) =352410760a(14) =2039099640a(15) =11878519460a(16) =69608606348a(17) =410056995475