python.输出1! +2! +3! +......n!

以下是Python代码，用于计算1! + 2! + 3! + …… + n!：

def factorial(n):
    if n == 0:
        return 1
    else:
        return n * factorial(n-1)

n = int(input("请输入一个正整数："))
sum = 0
for i in range(1, n+1):
    sum += factorial(i)
print("1! + 2! + 3! + ... + n! = ", sum)