My example of printing number.

ExLoopFun.cs

using System;
using System.Collections.Generic;

namespace ExLoopFun
{
    class Program
    {
        static void Main(string[] args)
        {
            Console.Write("Enter the positive integer number : ");

            var maxNum = 0;
            var isNumber = int.TryParse(Console.ReadLine(), out maxNum);

            if (isNumber && maxNum > 0)
            {
                var arryLength = (maxNum * 2) - 1;

                var arryResult = new int[arryLength];
                var listResult = new List<string>();

                var start = 0;
                var end = arryLength - 1;


                //Init array by 0
                for (int i = 0; i < arryResult.Length; i++)
                {
                    arryResult[i] = 0;
                }


                //Add 1 to array in the specific range
                for (int i = 0; i < maxNum; i++)
                {
                    for (int n = start; n <= end; n++)
                    {
                        arryResult[n] += 1;
                    }

                    //Collect all the element, convert to string and add result to list
                    var text = "";
                    for (int c = 0; c < arryResult.Length; c++)
                    {
                        text += arryResult[c].ToString();
                    }
                    listResult.Add(text);

                    //Shift the range of assign's index
                    start += 1;
                    end -= 1;
                }

                //Print linear
                for (int q = 0; q < listResult.ToArray().Length; q++)
                {
                    Console.WriteLine(listResult.ToArray()[q]);
                }

                //Print reverse + avoid last index
                for (int y = listResult.ToArray().Length - 2; y >= 0; y--)
                {
                    Console.WriteLine(listResult.ToArray()[y]);
                }

                Console.ReadLine();
            }
        }
    }
}