using System;

public class Program

{

    public static void Main()

    {

        for(int i = 0; i<30; i++)

        {

            Console.WriteLine(GetDayCode(DateTime.Now.AddDays(i)));

        }       

    }

​

    public static string GetDayCode(DateTime date)

        {

            string str = date.ToString("yyyyMMdd");

            return $"{str}: {CRC16_Martin(str, 1).ToString("X2")}";

        }

    private static int CRC16_Martin(string str, int n)

        {

            int num = 0;

            byte b = 0;

            byte b2 = 0;

            for (b = 0; b < str.Length; b = (byte)(b + 1))

            {

                num ^= (byte)str[b] << 8;

                for (b2 = 0; b2 < 8; b2 = (byte)(b2 + 1))

                {

                    num = (((num & 0x8000) == 0) ? (num << 1) : ((num << 1) ^ (4369 + n * 4)));

                }

            }

            return num & 0xFFFF;

        }

}