code: public static int getPrimeAt(int index) {
          if (index < 0 || index > PRIMES.length - 1) throw new ArrayIndexOutOfBoundsException("out of range " + index);
          return PRIMES[index];
      }
docs: Returns the i-th prime number in the sequence of
  all prime numbers below 19700. The first in the sequence
  (n=0) is the prime number 2.