User blog comment:Flavio61/Louis Epstein number list/@comment-27173506-20160118190252

His new Ultrex function reached f_w^2(n), but with the new version it reaches f_6(n) or f_w(n), it's not sufficiently clear.

The reason is that now it's applying the basic Ultrex function each time, instead of recursing on the last stage.