Mersenne Numbers

/*Check if a number is mersenne number or double mersenne number
Mersenne Numbers are the Numbers which are one less than a power of 2 i.e., (2^1-1),(2^2-1),(2^3-1).........
Some Mersenne Numbers are 1,3,7,15,31,63,127.......

Double Mersenne Numbers is a number of the form 2^(2^n-1)-1
Some Double Mersenne Numbers are 1,7,127,32767,2147483647.........*/
import java.util.Scanner;
public class Numbers
{
long number;
Numbers(long n)
{
number=n;
}
boolean isMersenne(){
long n=0;
for(int i=1;i<=20;i++)
{
n=(long)(Math.pow(2,i)-1);
if(n==number){
return true;
}
}
return false;
}
boolean isDoubleMersenne(){
long n=0;long pwr=0;
for(int i=1;i<=20;i++)
{
pwr=(long)Math.pow(2,i)-1;
n=(long)(Math.pow(2,pwr)-1);
if(n==number)
{
    return true;
}
}
return false;
}
public void genMersenneNos(){
    long num=0;
    System.out.println("Generated Mersenne numbers are :");
    for(int i=1;i<=10;i++)
    {
        num=(long)(Math.pow(2,i)-1);
        System.out.print(num+" ");
    }
    System.out.println();
}
public void genDoubleMersenneNos()
{
    long num=0;long pwr=0;
    System.out.println("Generated double Mersenne Numbers are:");
    for(int i=1;i<=6;i++)
    {
     pwr=(long)Math.pow(2,i)-1;
     num=(long)(Math.pow(2,pwr)-1);
     System.out.print(num+" ");
    }
    System.out.println();
}
public static void main(String[]args){
    Scanner in=new Scanner(System.in);
    long n;
    System.out.println("Enter a number");
    n=in.nextLong();
    Numbers numObject=new Numbers(n);
    if(numObject.isDoubleMersenne()==true)
    {
        System.out.println(n+"is a double Mersenne Number");
        numObject.genDoubleMersenneNos();
    }
    else if(numObject.isMersenne()==true)
    {
      System.out.println(n+"is a Mersenne Number");
      numObject.genMersenneNos();
    }
    else
    System.out.println(n+"is neither a Mersenne Number nor a Double Mersenne Number");
}
}