User blog comment:B1mb0w/Strong D Function Calculations/@comment-1605058-20150701125933/@comment-1605058-20150701140917

" You n.n\uparrow\uparrow n iterations of D(2,0,x) to get to f_{\varepsilon_0}(n)" I am not willing to take that for granted. I see absolutely no reason why this is supposed to be true.