User blog comment:Googology Noob/GoogolX/@comment-25601061-20151218154053

I have calculated the growth rates. a{X_n}b ~ {a,b,n,2}. a{X_[0]}b  ~  {a,b,1,3}. a{X_[n]}b  ~   {a,b,2,3}. a{X_[n,m]}b  ~ {a,b,m,3}. The limit of linear arrays is comparable to BEAF's linear arrays.