1.3.8.5

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace ConsoleApp2
{
    class Program
    {
        private static int Numb;
        static void Main(string[] args)
        {
            Console.WriteLine("Размер");
            Numb = Convert.ToInt32(Console.ReadLine());
            for (int x = 0; x < Numb; x++)
            {
                for (int y = 0; y < Numb; y++)
                {
                    Console.SetCursorPosition(x, y);
                    int min = x < y ? x : y;
                    int max = x > y ? x : y;
                    if (x + y < Numb)
                    {
                        Console.Write(min + 1);
                    }
                    else
                    {
                        Console.Write(Numb - max);
                    }
                }
            }
            Console.ReadLine();
        }
    }
}