请用户输入一个正整数n，输出从1到n每个数的阶乘，并计算这些阶乘之和。

def factorial(n):
  product = 1
  for i in range(1, n+1):
    product *= i
  return product

sum = 0
n = int(input('n = '))
for i in range(1, n+1):
    sum += factorial(i)
print('sum = ', sum)