using System;

public class Program

{

    public static void Main()

    {

        var store = new NumberStore();

        Console.WriteLine($"Original sequence: {store.ToString()}");

        int number = 16;

        ref int value = ref store.FindNumber(number);

        value *= 2;

        Console.WriteLine($"New sequence:      {store.ToString()}");

    }

    class NumberStore

    {

        int[] numbers = { 1, 3, 7, 15, 31, 63, 127, 255, 511, 1023 };

​

        public ref int FindNumber(int target)

        {

            for (int ctr = 0; ctr < numbers.Length; ctr++)

            {

                if (numbers[ctr] >= target)

                    return ref numbers[ctr];

            }

            return ref numbers[0];

        }

​

        public override string ToString() => string.Join(" ", numbers);

    }

}

​

// The example displays the following output:

//       Original sequence: 1 3 7 15 31 63 127 255 511 1023

//       New sequence:      1 3 7 15 62 63 127 255 511 1023