Data update

Task/Fortunate-numbers/C-sharp/fortunate-numbers.cs

@@ -0,0 +1,118 @@
+using System;
+using System.Collections.Generic;
+using System.Numerics;
+
+public class FortunateNumbers
+{
+    private const int CERTAINTY_LEVEL = 10;
+
+    public static void Main(string[] args)
+    {
+        var primes = PrimeSieve(400);
+        SortedSet<int> fortunates = new SortedSet<int>();
+        BigInteger primorial = BigInteger.One;
+
+        foreach (var prime in primes)
+        {
+            primorial *= prime;
+            int candidate = 3;
+            while (!BigInteger.Add(primorial, candidate).IsProbablyPrime(CERTAINTY_LEVEL))
+            {
+                candidate += 2;
+            }
+            fortunates.Add(candidate);
+        }
+
+        Console.WriteLine("The first 50 distinct fortunate numbers are:");
+        int count = 0;
+        foreach (var fortunate in fortunates)
+        {
+            if (count >= 50) break;
+            Console.Write($"{fortunate,4}{(count % 10 == 9 ? "\n" : "")}");
+            count++;
+        }
+    }
+
+    private static List<int> PrimeSieve(int aNumber)
+    {
+        var sieve = new bool[aNumber + 1];
+        var primes = new List<int>();
+
+        for (int i = 2; i <= aNumber; i++)
+        {
+            if (!sieve[i])
+            {
+                primes.Add(i);
+                for (int j = i * i; j <= aNumber && j > 0; j += i)
+                {
+                    sieve[j] = true;
+                }
+            }
+        }
+        return primes;
+    }
+}
+
+public static class BigIntegerExtensions
+{
+    private static Random random = new Random();
+
+    public static bool IsProbablyPrime(this BigInteger source, int certainty)
+    {
+        if (source == 2 || source == 3)
+            return true;
+        if (source < 2 || source % 2 == 0)
+            return false;
+
+        BigInteger d = source - 1;
+        int s = 0;
+
+        while (d % 2 == 0)
+        {
+            d /= 2;
+            s += 1;
+        }
+
+        for (int i = 0; i < certainty; i++)
+        {
+            BigInteger a = RandomBigInteger(2, source - 2);
+            BigInteger x = BigInteger.ModPow(a, d, source);
+            if (x == 1 || x == source - 1)
+                continue;
+
+            for (int r = 1; r < s; r++)
+            {
+                x = BigInteger.ModPow(x, 2, source);
+                if (x == 1)
+                    return false;
+                if (x == source - 1)
+                    break;
+            }
+
+            if (x != source - 1)
+                return false;
+        }
+
+        return true;
+    }
+
+    private static BigInteger RandomBigInteger(BigInteger minValue, BigInteger maxValue)
+    {
+        if (minValue > maxValue)
+            throw new ArgumentException("minValue must be less than or equal to maxValue");
+
+        BigInteger range = maxValue - minValue + 1;
+        int length = range.ToByteArray().Length;
+        byte[] buffer = new byte[length];
+
+        BigInteger result;
+        do
+        {
+            random.NextBytes(buffer);
+            buffer[buffer.Length - 1] &= 0x7F; // Ensure non-negative
+            result = new BigInteger(buffer);
+        } while (result < minValue || result >= maxValue);
+
+        return result;
+    }
+}