User blog comment:Boboris02/MBOT/@comment-30167082-20161218101337/@comment-1605058-20161218202142

Your last comment makes me even more convinced about one of my last points in the long comment above. In the single \(\neg\) in this short formula "describing" \(\Sigma(n)\) you are hiding an entire algorithm, description of which takes you a few lines.

You say that \(\neg\) doesn't have a meaning itself. I can agree with that. But this doesn't mean that you can throw arbitrary meaning upon it just by thinking about it in your head. In a formal, well-defined system, the meaning of \(\neg\) has to be stated somewhere. And in this case, it isn't.