Minimal integer n > 0 that for each prime if (p-1) | n then p | n

answer.js

// Problem:
// Find minimal integer number n > 0 that
// for any prime p:
// if (p - 1) | n then p | n
// where `|` means divide.
//

function gen_primes() {
  var N = 1000;
  var primes = Array(N);
  var i;
  
  for (i = 0; i < N; i++) {
      primes[i] = i;
  }
  
  primes[0] = primes[1] = -1;
  
  var step = 1;
  while (step < primes.length) {
     step++;
     if (primes[step] === -1) continue;
    
     for (i = step*2; i < primes.length; i += step) {
       primes[i] = -1;
     }
  }
  
  return primes.filter(function(x) { return x !== -1; });
}



var ps = [];
var n = 1;

var P = gen_primes()

var curr = 0;
while (curr < P.length) {
  var pp = P[curr++];
 
  if ( (n % pp) === 0 ) continue;
  
  if ( (n % (pp-1)) === 0 ) {
    n *= pp;
    ps.push(pp);
  }
}

console.log(ps);
console.log('n = ', n);

// ans: 1806