Better Way of Selecting Bit-size and Pseudo-Random Bit Generation

Is there a more elegant way of doing the bit size selection and pseudo-random binary bit generation than I am doing here? Actually I need to write an algorithm where the user is in control of the bit size (max 16 bit) of the random binary bit generated. This is the function I wrote however I am not sure if this is the smallest/most elegant. As this is scientific in need efficiency doesn't matter much but elegance of code and easy understandability does matter. So is there a more efficient/elegant way of doing the same?

private static string randomBit()
        {
            int bitSize = 0, input = 0;
            Console.Write("Input Bit Size (Maximum is 16 Bit): ");
            input = Convert.ToInt32(Console.ReadLine());
            Random choice = new Random();
            if (input == 0 || input > 16)
            {
                bitSize = 0;
            }
            else if (input == 1)
            {
                bitSize = 1;
            }
            else if (input == 2)
            {
                int randomChoice = choice.Next(2, 3);
                bitSize = randomChoice;
            }
            else if (input == 3)
            {
                int randomChoice = choice.Next(4, 7);
                bitSize = randomChoice;
            }
            else if (input == 4)
            {
                int randomChoice = choice.Next(8, 15);
                bitSize = randomChoice;
            }
            else if (input == 5)
            {
                int randomChoice = choice.Next(16, 31);
                bitSize = randomChoice;
            }
            else if (input == 6)
            {
                int randomChoice = choice.Next(32, 63);
                bitSize = randomChoice;
            }
            else if (input == 7)
            {
                int randomChoice = choice.Next(64, 127);
                bitSize = randomChoice;
            }
            else if (input == 8)
            {
                int randomChoice = choice.Next(128, 255);
                bitSize = randomChoice;
            }
            else if (input == 9)
            {
                int randomChoice = choice.Next(256, 511);
                bitSize = randomChoice;
            }
            else if (input == 10)
            {
                int randomChoice = choice.Next(512, 1023);
                bitSize = randomChoice;
            }
            else if (input == 11)
            {
                int randomChoice = choice.Next(1024, 2047);
                bitSize = randomChoice;
            }
            else if (input == 12)
            {
                int randomChoice = choice.Next(2047, 4095);
                bitSize = randomChoice;
            }
            else if (input == 13)
            {
                int randomChoice = choice.Next(4096, 8191);
                bitSize = randomChoice;
            }
            else if (input == 14)
            {
                int randomChoice = choice.Next(8192, 16383);
                bitSize = randomChoice;
            }
            else if (input == 15)
            {
                int randomChoice = choice.Next(16384, 32767);
                bitSize = randomChoice;
            }
            else if (input == 16)
            {
                int randomChoice = choice.Next(32768, 65535);
                bitSize = randomChoice;
            }
            string binary = Convert.ToString(bitSize, 2);
            return binary;
        }

Also as a second question, if I press Enter twice when the code is asking for bit size, it returns an exception error. Is there a way to bypass the same?
Thanks.