# Counting Triangles

Time Limit: 1 Second Memory Limit: 32768 KB

Given an equilateral triangle with n the length of its side, program to count how many triangles in it.

## 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 13Submit

Source: ZOJ Monthly, June 2003