Python| sympy.divisor_sigma() 方法

借助sympy.divisor_sigma()方法，我们可以找到除数函数$\sigma_k(n)$对于正整数n 。 divisor_sigma(n, k)等于n的所有除数的总和，以k或sum([x**k for x in divisors(n)])的幂次幂计算。

Syntax: divisor_sigma(n, k)

Parameter:
n – It denotes an integer.
k – It denotes an integer(optional). Default for k is 1.

Returns: Returns the sum of all the divisors of n raised to the power of k.

示例 #1：

# import divisor_sigma() method from sympy
from sympy.ntheory import divisor_sigma
  
n = 8
  
# Use divisor_sigma() method 
divisor_sigma_n = divisor_sigma(n) 
      
print("divisor_sigma({}) =  {} ".format(n, divisor_sigma_n)) 
# 1 ^ 1 + 2 ^ 1 + 4 ^ 1 + 8 ^ 1 = 15

输出：

divisor_sigma(8) =  15 

示例 #2：

# import divisor_sigma() method from sympy
from sympy.ntheory import divisor_sigma
  
n = 15
k = 2
  
# Use divisor_sigma() method 
divisor_sigma_n = divisor_sigma(n, k) 
      
print("divisor_sigma({}, {}) =  {} ".format(n, k, divisor_sigma_n)) 
# 1 ^ 2 + 3 ^ 2 + 5 ^ 2 + 15 ^ 2 = 260

输出：

divisor_sigma(15, 2) =  260