G.f.: A(x) = 1+x*(1+x*(1+x*(...(1+x*(...)^(3^n) )...)^27)^9)^3.

A184575

G.f.: A(x) = 1+x*(1+x*(1+x*(...(1+x*(...)^(3^n) )...)^27)^9)^3.

Terms

    a(0) =1a(1) =1a(2) =3a(3) =30a(4) =892a(5) =76554a(6) =19138212a(7) =14126533902

External references