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Author: M-F-Tushar

OOP in Java/Chapter 10 - Object-Oriented Thinking/Code_Example/Exercise10_19.java

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+package ch_10;
+
+import java.math.BigInteger;
+
+/**
+ * 10.19 (Mersenne prime) A prime number is called a Mersenne prime if it can be written in the form 2^p - 1 for some
+ * positive integer p. Write a program that finds
+ * all Mersenne primes with p … 100 and displays the output as shown below.
+ * (Hint: You have to use BigInteger to store the number, because it is too big to
+ * be stored in long. Your program may take several hours to run.)
+ */
+public class Exercise10_19 {
+    static int P = 2;
+    static BigInteger TWO = BigInteger.valueOf(2L);
+
+    public static void main(String[] args) {
+        System.out.print("p     2^p - 1");
+
+        while (P <= 100) {
+            BigInteger mersennePrime = TWO.pow(P).subtract(BigInteger.ONE);
+            if (mersennePrime.isProbablePrime(1)) {
+                System.out.print("\n" + P + "     " + mersennePrime.toString());
+                System.out.println();
+                P++;
+            }
+        }
+    }
+
+}
+