// WHILE LOOP
import java.util.Scanner;

public class PowersOf2
{
    public static void main(String[] args)
    {
        int numPowersOf2;        // How many powers of 2 to compute
        int nextPowerOf2 = 1;    // Current power of 2 (starting with 2^0 = 1)
        int exponent = 0;        // Exponent for current power of 2 (starting with 0)
        Scanner scan = new Scanner(System.in);

        System.out.println("How many powers of 2 would you like printed?");
        numPowersOf2 = scan.nextInt();

        // Print a message saying how many powers of 2 will be printed
        System.out.println("Here are the first " + numPowersOf2 + " powers of 2:");

        // Print the powers of 2
        while (exponent < numPowersOf2)
        {
            System.out.println("2^" + exponent + " = " + nextPowerOf2);

            // Compute the next power of 2 by doubling the current one
            nextPowerOf2 *= 2;

            // Increment exponent
            exponent++;
        }
    }
}