1:  using Xint = System.Numerics.BigInteger;

   2:   

   3:   

   4:  namespace Luschny.Math.Factorial

   5:  {

   6:      /// <summary> An interface for the factorial function

   7:      /// n! = 1*2*3*...*n

   8:      /// for nonnegative integer values n.

   9:      /// </summary>

  10:      public interface IFactorialFunction

  11:      {

  12:          string Name { get; }

  13:          Xint Factorial(int n);

  14:      }

  15:   

  16:  } // endOfIFactorialFunction