/* 	ESC101 : Fundamental of Computing Lab 6 for 10th September 2008
	
	Write a JAVA program to find the approximate value of Erdos Brownian Constant, by calculating the first 30 terms of the summation.
	Your program has to design and use the following methods:	
		int noOfDivisors (int n): returns number of divisors of n.
		int power (int n, int k): returns nk.
	In the main method, declare a double variable sum and initialize it to 0. Call both of the above methods in a loop for each value of n to get each term of the sum.

*/

class Erdos
{

	//Method to calculate n^k
    public static int power(int n, int k)
    {
		int power = 1;
		int i;
		for(i=0;i<k;i++)
	  	  power = power * n;
		return power;
    }

	//Method to calculate the number of divisors of n	
    public static int noOfDivisors(int n)
    {
		int div_cnt = 0;
		int i;
		for(i=1;i<=n;i++) {
		    if((n % i) == 0)
				div_cnt++;
		}
		return div_cnt;
    }
    
	public static void main(String args[])
    {
		double sum = 0;
		int i,nDiv, nPow;
		int n = 30; //The question says to to find the approximate value of E, by calculating the first 30 terms of the above summation
		double term;
		for(i=1;i<=n;i++){
		    nDiv = noOfDivisors(i); //For each i we calculalte the no of divisors
		    nPow = power(2, i); 	//For each i we calculate 2^i 
		    term = (double)nDiv / (double)nPow; 	// We no calculate the individual term of the series
		    sum = sum + term; 	//Finally add the term to the series sum.
		}
		System.out.println(sum);
    }
}