G.f.: A(x) = 1 + x*(1 + x*(1 + x*(...(1 + x*(...)^(6n))...)^18)^12)^6.
A138216
G.f.: A(x) = 1 + x*(1 + x*(1 + x*(...(1 + x*(...)^(6n))...)^18)^12)^6.
Terms
- a(0) =1a(1) =1a(2) =6a(3) =87a(4) =2072a(5) =69051a(6) =2960496a(7) =155190175a(8) =9614870340a(9) =687262107456
External references
- oeis: A138216