@VTCAKAVSMoACE I'm becoming convinced again that it's impossible. There is no way to take x,y as input and have a stack like [x,y,x,y], which is what I would need in order to calculate such a formula.
I made a (objectively funny) joke that Alex did not get (as always) but the rest thought it was funny. Doorknob was laughing so hard he accidentaly hit the delete button.
@VTCAKAVSMoACE: I'm actually having difficulty determining whether I can even do factorial. A while loop will continue until the top of stack is 0. I can build up a stack of [n,n-1,...,2,1] and multiply it together, but I have no way of knowing when it's done so I can exit just before it gets multiplied by 0.
The "Report" area isn't simply printing a file though. It can be generated by, say, a program written by the KOTH author for fancy formatting or other stuff.