User blog comment:All Things Logical/How to generate big numbers/@comment-80.98.179.160-20180108150753

OK, then define multiple arguments: A(1,n)=A^n(n), A(n,m)=A(n-1,A(n-1,...(m times)...A(n-1,n)...(m times)...))

Continue with A(googol,googol).