JSFiddle - React, Tailwind, and code Playground

by chridam

JavaScript

function prime(a){
     if (a%2==0)
         { return 2;}
     else if (a%3==0)
     { 
      if (a!=3) {return 2;}
      else {return 1;}
     }
     else
     {
     var a2=Math.floor(Math.sqrt(a))
     for(i=5,c=2;i<=a2;c++)
      {
       if (a%i==0) {return 2;}
       if (c%2==0) {i+=2}
       else {i+=4}
      }
       if (i>a2) {return 1;}
     }
}
var x=0;
for(n=1;n=7;n+=2){
    if(prime(n*n-3*(n-1))==1){x=x+1}
    if(prime(n*n-2*(n-1))==1){x=x+1}
    if(prime(n*n-(n-1))==1){x=x+1}
}
console.log(100*(2*n-1)/x)