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

Terms

a(0) =1a(1) =1a(2) =-5a(3) =-15a(4) =165a(5) =630a(6) =-8151a(7) =-33780a(8) =474045a(9) =2052495a(10) =-30206330a(11) =-134392230a(12) =2040588775a(13) =9248893360a(14) =-143569282680a(15) =-659546365020