For positive integer , the -function is defined by
where the numbers are called hyperfactorials by Sloane and Plouffe (1995). It is related to the Barnes G-function by
The first few values of for , 2, ... are 1, 1, 4, 108, 27648, 86400000, 4031078400000, ... (OEIS A002109).
More things to try:
Weisstein, Eric W. "K-Function." From MathWorld--A Wolfram Web Resource. https://mathworld.wolfram.com/K-Function.html
,
the 
-function is defined by
are called hyperfactorials by Sloane and Plouffe
(1995). It is related to the Barnes G-function
by
![K(n)=([Gamma(n)]^(n-1))/(G(n)).](/images/equations/K-Function/NumberedEquation1.svg)
for 
, 2, ... are 1, 1, 4, 108, 27648, 86400000,
4031078400000, ... (OEIS A002109).
