﻿ Java exercises: Check if a number is Mersenne number or not - w3resource

# Java Exercises: Check if a number is Mersenne number or not

## Java Numbers: Exercise-22 with Solution

Write a program to check if a number is Mersenne number or not.

In mathematics, a Mersenne number is a prime number that can be written in the form Mn = 2n − 1 for some integer n.
The first four Mersenne primes are 3, 7, 31, and 127

Test Data
Input a number: 127

Pictorial Presentation: Sample Solution:

Java Code:

``````import java.util.Scanner;
import java.math.BigInteger;
public class Example22 {

public static void main(String args[])
{
Scanner in = new Scanner(System.in);
System.out.print("Input a number: ");
int n = in.nextInt();
int n1 = n + 1;

int power = 0;
int ans = 0;
for(int i=0;;i++)
{
power=(int)Math.pow(2,i);
if(power>n1)
{
break;
}
else if(power==n1)
{
System.out.println(n+" is a Mersenne number.");
ans=1;
}
}
if(ans==0)
{
System.out.println(n+" is not a Mersenne number.");
}
}
}
```
```

Sample Output:

```Input a number: 127
127 is a Mersenne number.
```

Flowchart: Java Code Editor: