Expansion of (1/3)*(1 - (1-9*x-9*x^2)^(1/3)).

Terms

a(0) =0a(1) =1a(2) =4a(3) =21a(4) =138a(5) =999a(6) =7683a(7) =61542a(8) =507663a(9) =4281849a(10) =36748998a(11) =319845591a(12) =2816007714a(13) =25032803841a(14) =224355173193