Problem Description
Given an equilateral triangle with n the length of its side, program to count how many triangles in it.HDU 1396 Counting Triangles
Input
The length n (n <= 500) of the equilateral triangle's side, one per line.
process to the end of the file
Output
The number of triangles in the equilateral triangle, one per line.
Sample Input
1 2 3
Sample Output
1 5 13