Count All Valid Pickup and Delivery Options

export function countOrders(n: number): number {
  const MOD = 10 ** 9 + 7;
 
  let answer = 1;
  for (let i = 2; i <= n; i++) {
    answer = (answer * (2 * i - 1) * i) % MOD;
  }
 
  return answer;
}