An equilateral white triangle gets split into four equilateral sub-triangles and the one at the center gets colored red. This process is repeated for all available white squares in each iteration. You are given an integer m for the number of lines following and an integer n in each line following that for the number of iterations for each of which we want an answer.  

What is the total number of triangles after each iteration

For example n = 1 Answer = 5  

                     n = 2, Answer = 17  

                     n = 3, Answer = 53 (?)   

namespace TriangleCounter  

{  

    class Program  

    {  

        static void Main(string[] args)  

        {  

            int n;  

            Int32.TryParse(Console.ReadLine(), out n);  

            for (int i = 0; i < n; i++)  

            {  

                 int m;  

                 Int32.TryParse(Console.ReadLine(), out m);  

                 Console.WriteLine("{0}", GetTriangleCount(m));  

            }  

        } 

        static double GetTriangleCount(int m)  

        {  

            double white = 1;  

            double red = 0;  

            double result = 1;  

            for (int i = 0; i < m; i++)  

            {  

                red = white;  

                white = white * 3;  

                result = result + white + red;  

            }  

            return result;  

        }  

    }  

}  

We could also do this recursively as GetTriangleCountRecursive (n) = 3 * GetTriangleCountRecursive (n-1) + 1 + 1 and the terminating condition of n ==0 => 1