User blog comment:B1mb0w/Strong D Function and f epsilon nought (n)/@comment-5529393-20150805104604

You can't use Rule: LN until you show that $$D(l-1,0,n) = f_\phi^{n-1}(f_\phi(3))$$. All you've shown is that $$D(1,0,2) > f_{\omega+1}(3)$$.