G.f. A(x) satisfies A(A(A(x))) = x+3*x^2+9*x^3.

Terms

a(0) =1a(1) =1a(2) =1a(3) =-8a(4) =28a(5) =-26a(6) =-386a(7) =2701a(8) =-5399a(9) =-42155a(10) =358615a(11) =-354212a(12) =-10419524a(13) =52825312a(14) =236952352a(15) =-3103798967a(16) =-3013742105a(17) =176201013745a(18) =-164790760103