Generate first n Bernoulli numbers

bernoulli.js

function b(max) {
  const B = Array(max + 1).fill(0);
  B[0] = 1;
  B[1] = 1/2;

  for (let n = 2; n <= max; n += 2) {
    let sum = 0;
    let c = 1;

    for (let j = 0, j2 = n; j <= n / 2; j += 2, j2 -= 2) {
      let tmp = (j - 1) / (n + 1 - j) * B[j];
      if (j2 !== j) tmp += (j2 - 1) / (n + 1 - j2) * B[j2];
      tmp *= c / n;
      sum += tmp;
      c *= (n - j) * (n - j - 1) / ((j + 1) * (j + 2));
    }

    sum *= n % 2 ? 1 : -1;
    B[n] = sum;
  }

  return B;
}

console.time("B(20000)");
b(20000);
console.timeEnd("B(20000)");