# scipy.special.factorialk

scipy.special.factorialk(n, k, exact=True)

  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 have

  > factorialk(n, 1) = factorial(n)

  > factorialk(n, 2) = factorial2(n)

  Parameters
    n int

      Calculate multifactorial. If n < 0, the return value is 0.

    k int

      Order of multifactorial.

    exact bool, optional

      If exact is set to True, calculate the answer exactly using integer arithmetic.

  Returns
    val int

      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

scipy.special.factorial2 scipy.special.shichi