In Mathematics, a Mersenne prime is a number that can be written in the form M(n) = 2^n − 1 for some integer n and is actually a prime number.
For example − The first four Mersenne primes are 3, 7, 31, and 127
We are required to write a JavaScript function that takes in a number and checks whether it is a Mersenne prime or not. Let’s write the code for this function
Example
const isPrime = num => { let i = 2; while(i <= num / 2){ if(num % i++ === 0){ return false; }; }; return true; } const mersennePrime = num => { if(!isPrime(num)){ return false; }; let i = 0, n = num+1; while(n !== 1){ if(n % 2 !== 0){ return false; }; n /= 2; }; return true; }; console.log(mersennePrime(31)); console.log(mersennePrime(127)); console.log(mersennePrime(3)); console.log(mersennePrime(37)); console.log(mersennePrime(87)); console.log(mersennePrime(7));
Output
The output in the console will be −
true true true false false true