4378: 求1+4+7+10+……+n之和
Memory Limit:128 MB
Time Limit:1.000 S
Judge Style:Text Compare
Creator:
Submit:80
Solved:36
Description
求1+4+7+10+……+n的等差数列之和,公差为3。( 1<=n<=1000)
Input
一个整数n( 1<=n<=1000)
Output
等差数列的和
Sample Input Copy
100
Sample Output Copy
1717