pollard

const makeG = n => x => (x ** 2 + 1) % n;

const gcd = (a, b) => (b === 0 ? a : gcd(b, a % b));

const pollard = n => {

  const g = makeG(n);

  let x = 1;
  let y = 2;
  let d = 1;
  while (d === 1) {

    x = g(x);
    y = g(g(y));
    d = gcd(Math.abs(x - y), n);

  }

  return d === n ? false : d;

};