a(n) = f_n(2), with f_0(x) = x+2, f_n+1(x) = (f_n)^x(x).

A274992

a(n) = f_n(2), with f_0(x) = x+2, f_n+1(x) = (f_n)^x(x).

Terms

    a(0) =4a(1) =6a(2) =18a(3) =6973568802

External references