Find least Prime Factor.

leastPrimeFactor.js

function leastPrimeFactor(x){
 let seq = Array(x+1);
 seq[1] = 1;
 for(let i = 2;i<=x;i++){
 	if(!seq[i]){
  	seq[i] = i;
    for(let j=2*i; j<=x;j+=i){
    	if(!seq[j])
      	seq[j] = i;
    }
  }
 }
 
 seq.forEach((e,i)=>{
 	console.log(`Least Prime factor of ${i}: ${e}`);
 })
}

leastPrimeFactor(15);

/*
Least Prime factor of 1: 1
Least Prime factor of 2: 2
Least Prime factor of 3: 3
Least Prime factor of 4: 2
Least Prime factor of 5: 5
Least Prime factor of 6: 2
Least Prime factor of 7: 7
Least Prime factor of 8: 2
Least Prime factor of 9: 3
Least Prime factor of 10: 2
Least Prime factor of 11: 11
Least Prime factor of 12: 2
Least Prime factor of 13: 13
Least Prime factor of 14: 2
Least Prime factor of 15: 3
*/