Python 求n阶的和

 1 #coding:utf-8
 2 #__author__ = ‘Diva‘
 3
 4 def sum(n):
 5     if not n.isdigit():    # 对输入的参数做判断，不符合就退出
 6         return False
 7
 8     nn = int(n)
 9     tmp = 1
10     sum = 0
11
12     for i in range(1, nn + 1):
13         tmp = tmp * i
14         sum = sum + tmp
15
16     print(‘%d! 的和是 %d ‘ % (nn, sum))
17
18 if __name__ == ‘__main__‘:
19     print(‘这个程序是用来计算n阶的和‘)
20     num = raw_input(‘请输入一个数字：‘)
21     sum(num)