Formulas.java

import java.util.Scanner;

/**
 * The contents of this file are not directly bound to a normal Algorithms class
 * Here I plan to store some known Algorithms that represent proven Mathematical formulas
 * for computing calculations that may appear in my programming assignments
 *
 * @author Rodrigo Alves
 *
 */
public class Formulas {

	/**
	 * Computes the sum of the squares of the first n positive integers
	 * http://www.texpaste.com/n/9a6oaoqf
	 * @param n
	 * @return the sum of the squares of the first n positive integers
	 */
	public static int integerSquareSum(int n) {
		return ((n * (n + 1)) * ((2*n) + 1)) / 6;
	}

	public static void main(String[] args) {
    Scanner input = new Scanner(System.in);

		/* System.out.println(integerSquareSum(3)); // 1^2 + 2^2 */

		/* System.out.println(integerSquareSum(10)); // 1^2 + 2^2 + 3^2 + 4^2 + 5^2 + 6^2 + 7^2 + 8^2 + 9^2 + 10^2 */
	  System.out.println("Calculate the sum of the squares of the first n integers. Enter n:");
    int n = input.nextInt();

    System.out.println(integerSquareSum(n));
  }
}