Data update

Task/Fortunate-numbers/Java/fortunate-numbers.java

@@ -0,0 +1,41 @@
+import java.math.BigInteger;
+import java.util.BitSet;
+import java.util.NavigableSet;
+import java.util.TreeSet;
+
+public final class FortunateNumbers {
+
+	public static void main(String[] aArgs) {
+		BitSet primes = primeSieve(400);		
+		NavigableSet<Integer> fortunates = new TreeSet<Integer>();
+        BigInteger primorial = BigInteger.ONE;
+		
+		for ( int prime = 2; prime >= 0; prime = primes.nextSetBit(prime + 1) ) {
+		    primorial = primorial.multiply(BigInteger.valueOf(prime));
+		    int candidate = 3;
+		    while ( ! primorial.add(BigInteger.valueOf(candidate)).isProbablePrime(CERTAINTY_LEVEL) ) {
+		    	candidate += 2;
+		    }
+		    fortunates.add(candidate);
+		}
+		
+		System.out.println("The first 50 distinct fortunate numbers are:");
+		for ( int i = 0; i < 50; i++ ) {
+			System.out.print(String.format("%4d%s", fortunates.pollFirst(), ( i % 10 == 9 ? "\n" : "" )));
+		}
+	}
+	
+	private static BitSet primeSieve(int aNumber) {
+		BitSet sieve = new BitSet(aNumber + 1);
+		sieve.set(2, aNumber + 1);
+		for ( int i = 2; i <= Math.sqrt(aNumber); i = sieve.nextSetBit(i + 1) ) {
+			for ( int j = i * i; j <= aNumber; j = j + i ) {
+				sieve.clear(j);
+			}
+		}		
+		return sieve;
+	}
+	
+	private static final int CERTAINTY_LEVEL = 10;
+
+}