HP-35 origin

[Thomas Okken]

(06-19-2018 10:22 AM)StephenG1CMZ Wrote:  

(06-18-2018 12:02 AM)brickviking Wrote:  Pi !!!

I am curious - How did you parse that expression?

X!! Is not the same as (X!)! If you have heard of double-factorials, although of course it is if you haven't, ! Being an ambiguous mathematical symbol.

Is that x!!! (A triple factorial?)
(X!!)! (Factorial of a double factorial)
(X!)!! (Double factorial of a factorial)
((X!)!)! (Factorial of a factorial of a factorial)

I'd vote for the triple factorial interpretation. Although I noticed that Wolfram Alpha interprets it as (Pi !!)! instead, so it recognizes the double factorial but not higher-order multifactorials. Also interesting is that it appears to have an analytic continuation of the double factorial; I wonder if such continuations exist for higher-order multifactorials as well?