User blog comment:MilkyWay90/Finishing my very first notation - The Generalized Factorial/@comment-35470197-20190710234255/@comment-31966679-20190712150016

> I could not understand the meaning. You meant that \(!\) does not appear in valid expression in \(F\), right?

Whoops, typo!

> The same symbols appearing in a a single equality is supposed to be the same value. Therefore you need to write something like \(F_!(@_1,n,l!,@_2)\) instead of \(F_!(@,n,l!,@)\).

Okay

> 1. and 2.

Oh sorry, that was a typo