User blog comment:LittlePeng9/Higher order set theory/@comment-24509095-20141010045633/@comment-1605058-20141010050433

First of all, \(Rayo_{O_O}(10^{10^{100}})\) is already at least as large as Rayo nunber. Iterating the function twice already gives us the number greater than the largest number definable in Rayo number symbols. And then we iterate 98 more times.