Python | sympy.factorial2() method

With the help of sympy.factorial2() method, we can find the Double factorial. Double factorial of a number is given by –

Syntax: factorial2(n) Parameter: n – It denotes the number whose double factorial is to be calculated. Returns: Returns the double factorial of number, i. e., n.

Example #1:

# import sympy
from sympy import *

n = 10
print("Value of n = {}".format(n))

# Use sympy.factorial2() method
factorial2_n = factorial2(n)

print("Double factorial of n : {}".format(factorial2_n))

Output:

Value of n = 10
Double factorial of n : 3840

Example #2:

# import sympy
from sympy import *

n = -3
print("Value of n = {}".format(n))

# Use sympy.factorial2() method
factorial2_n = factorial2(n)

print("Double factorial of n : {}".format(factorial2_n))

Output:

Value of n = -3
Double factorial of n : -1