Java BigInteger calculate Mersenne prime

import java.math.BigInteger;

public class Main {
  /** Main method */
  public static void main(String[] args) {
    // Display table header
    System.out.println("p       2^p - 1");

    // Display all Mersenne primes with p <= 31
    for (BigInteger p = new BigInteger("2"); 
      p.compareTo(new BigInteger("100")) <= 0; 
      p = p.add(new BigInteger("1"))) {
      if (isPrime(p)) {
        System.out.printf("%-3d", p);
        System.out.println("       " + mersennePrime(p));
      }//from  ww  w .  ja  v a 2 s.  c  om
    }
  }

  /** Method mersennePrime finds and returns the mersenne prime of n */
  public static BigInteger mersennePrime(BigInteger n) {
    BigInteger two = new BigInteger("2");
    BigInteger x = new BigInteger("2");
    for (BigInteger i = new BigInteger("1"); i.compareTo(n) < 0; 
      i = i.add(new BigInteger("1"))) {
      x = x.multiply(two);
    }
    return x.subtract(new BigInteger("1")); 
  }

  /** Check whether number is prime */
  public static boolean isPrime(BigInteger n) {
    for (BigInteger d = new BigInteger("2"); 
        d.compareTo(n.divide(new BigInteger("2"))) <= 0; 
        d = d.add(new BigInteger("1"))) {
      if (n.remainder(d).compareTo(new BigInteger("0")) == 0) { // If true, number is not prime
        return false; // Number is not a prime
      }
    }
    return true; // Number is prime
  }
}