scipy.special.factorialk¶
-
scipy.special.
factorialk
(n, k, exact=True)[source]¶ Multifactorial of n of order k, n(!!…!).
This is the multifactorial of n skipping k values. For example,
factorialk(17, 4) = 17!!!! = 17 * 13 * 9 * 5 * 1
In particular, for any integer
n
, we havefactorialk(n, 1) = factorial(n)
factorialk(n, 2) = factorial2(n)
- Parameters
- nint
Calculate multifactorial. If n < 0, the return value is 0.
- kint
Order of multifactorial.
- exactbool, optional
If exact is set to True, calculate the answer exactly using integer arithmetic.
- Returns
- valint
Multifactorial of n.
- Raises
- NotImplementedError
Raises when exact is False
Examples
>>> from scipy.special import factorialk >>> factorialk(5, 1, exact=True) 120 >>> factorialk(5, 3, exact=True) 10