Write a program in C# Tribonacci series

class Program

    {

        static void Main(string[] args)

        {

            int num, a = 1, b = 1, c = 1, d = 0, i;

            Console.WriteLine("Enter the number");

            num = int.Parse(Console.ReadLine());

            Console.Write(a + " ");

            Console.Write(b + " ");

            Console.Write(c + " ");

            for (i = 3; i < num; i++)

            {

                d = a + b + c;

                Console.Write(d + " ");

                a = b;

                b = c;

                c = d;

            }

            Console.WriteLine();

            Console.ReadLine();

        }

    }