Find Summation of a geometric sequence

Console.Title = "Find Summation of a geometric sequence";

            Console.Write("Enter the number of numbers : ");
            double n = Convert.ToDouble(Console.ReadLine());
            Console.Write("Enter the first number : ");
            double f = Convert.ToDouble(Console.ReadLine());
            Console.Write("Enter the base : ");
            double b = Convert.ToDouble(Console.ReadLine());

            Console.WriteLine();
            Console.WriteLine("Sequence will be : ");
            Console.Write($"{f} ");
            double sum = f;
            for (int i = 0;i<n-1;i++)
            {
                double x = f * b;
                Console.Write($"{x} ");
                f = x;
                sum += f;
            }
            Console.WriteLine();
            Console.WriteLine("The Sum of the sequence is : "+sum);
            Console.ReadKey();