Sync

Task/Multifactorial/C-sharp/multifactorial.cs

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+namespace RosettaCode.Multifactorial
+{
+    using System;
+    using System.Linq;
+
+    internal static class Program
+    {
+        private static void Main()
+        {
+            Console.WriteLine(string.Join(Environment.NewLine,
+                                          Enumerable.Range(1, 5)
+                                                    .Select(
+                                                        degree =>
+                                                        string.Join(" ",
+                                                                    Enumerable.Range(1, 10)
+                                                                              .Select(
+                                                                                  number =>
+                                                                                  Multifactorial(number, degree))))));
+        }
+
+        private static int Multifactorial(int number, int degree)
+        {
+            if (degree < 1)
+            {
+                throw new ArgumentOutOfRangeException("degree");
+            }
+
+            var count = 1 + (number - 1) / degree;
+            if (count < 1)
+            {
+                throw new ArgumentOutOfRangeException("number");
+            }
+
+            return Enumerable.Range(0, count)
+                             .Aggregate(1, (accumulator, index) => accumulator * (number - degree * index));
+        }
+    }
+}