G.f. A(x) satisfies A(x) = (1 - 9*x*A(x))^(2/3).

Terms

a(0) =1a(1) =-6a(2) =27a(3) =-90a(4) =189a(5) =0a(6) =-1782a(7) =6318a(8) =0a(9) =-90882a(10) =360126a(11) =0a(12) =-5985819a(13) =24931800a(14) =0a(15) =-446371074a(16) =1912892355a(17) =0a(18) =-35840971530a(19) =156454458930a(20) =0a(23) =0a(26) =0a(29) =0