User blog comment:MilkyWay90/another attempt at making a fast-growing function/@comment-35392788-20180706153145/@comment-31966679-20180706182727

\(set_{n}\) would be the \(n\)th element of \(set\).

\(set_{0} = A\)

\(set_{0}(n) = A(n)\)

\(set_{6}(n) = F(n)\) And so on...