Multifactorial
A generalization of the factorial and double factorial,
n! = n(n-1)(n-2)...2·1
(1)
n!! = n(n-2)(n-4)...
(2)
n!!! = n(n-3)(n-6)...,
(3)
etc., where the products run through positive integers.
The following table lists the values of the first few multifactorials for n=1, 2, ....
See also
Double Factorial, Factorial, Gamma Function, Pochhammer Symbol, Reciprocal Multifactorial ConstantExplore with Wolfram|Alpha
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References
Sloane, N. J. A. Sequences A000142/M1675, A006882/M0876, A007661/M0596, and A007662/M0534 in "The On-Line Encyclopedia of Integer Sequences."Referenced on Wolfram|Alpha
MultifactorialCite this as:
Weisstein, Eric W. "Multifactorial." From MathWorld--A Wolfram Resource. https://mathworld.wolfram.com/Multifactorial.html