I would like to typeset an old fashioned factorial symbol and was wondering whether there was an elegant way of doing this that scales with font size. Ideally what I would like is to invoke
in mathematics mode and get as an output the contents surrounded by a box frame with only two sides, the left and the bottom.
The output would look something like
|__ with the contents nestling inside the L-shaped corner.
I've looked through different packages but couldn't find anything appropriate. So I've solved the problem for the time being with basic underlines and rules with appropriate spaces but my solution doesn't scale all that well and is certainly quite ugly code!