User blog comment:Googleaarex/My number is bigger! (Googology Wiki version)/@comment-24509095-20140921170054/@comment-25371339-20140921180053

What about:

R(n) = F(F(F(...(F(F(n)))...))) w/ n levels (in your F function)

My number is R(R(R(...(R(R(googolplex)))...))) w/ googolplex nestings