Any chance of a post summarizing all of the building block posts for this topic, like you did with your physics posts?
I hate to be a beggar, but that would be very helpful.

"I don't remember writing this. Did somebody else write this using the same handle as me or did I write this and forget it?"

My son's name is also Bort.

So... Should it be obvious that the nth difference is n factorial? I'm afraid I don't have intuitive knowledge of all the properties of the factorial function.