Correct the prime check algorithm

There are no prime numbers smaller than 2 and numbers greater than and divisible by 2 are not prime.

Maths/PrimeCheck.java

@@ -21,6 +21,12 @@ public class PrimeCheck {
      * @return {@code true} if {@code n} is prime
      */
     public static boolean isPrime(int n) {
+        if (n == 2) {
+            return true;
+        }
+        if (n < 2 || n % 2 == 0) {
+            return false;
+        }
         for (int i = 3; i <= Math.sqrt(n); i += 2) {
             if (n % i == 0) {
                 return false;