解法一：while循环求解
n = int(input())
jie = 1
sum = 0
i = 1
while n >= i:
jie = jie * i
sum = sum + jie
i = i + 1
print(sum)
解法二：递归求解
def jie(n):
if n == 1:
return 1
else:
return n*jie(n-1)
n = int(input())
sum = 0
for i in range(1,n+1):
sum = sum + jie(i)
print(sum)
