C# Online Compiler | .NET Fiddle

using System;
using System.Linq;
					
public class Program
{
	public static void Main()
	{
		Console.WriteLine(Plus.Pattern(11));
	}
	
	
	public static class Plus
	{
	  public static string Pattern(int n)
	  {
			return n < 1 ? "" :
				string.Join("\n", Enumerable.Range(1, n - 1).Select(
					i =>
					string.Join("", Enumerable.Repeat(" ", n - 1))
					+
					string.Join("", Enumerable.Repeat(i, n).Select(j => j % 10))
					+
					string.Join("", Enumerable.Repeat(" ", n - 1))
				)) + "\n" +
	
				string.Join("\n",
					Enumerable.Repeat(
						string.Join("",
							Enumerable.Range(1, n - 1).Select(j => j % 10).Concat(
							Enumerable.Repeat(1, n).Select(j => n % 10).Concat(
								Enumerable.Range(1, n - 1).Reverse().Select(j => j % 10)
								)
							)
						)
					, n)
				)
				+ "\n"
				+ string.Join("\n", Enumerable.Range(1, n - 1).Reverse().Select(
					i =>
					string.Join("", Enumerable.Repeat(" ", n - 1))
					+
					string.Join("", Enumerable.Repeat(i, n).Select(j => j % 10))
					+
					string.Join("", Enumerable.Repeat(" ", n - 1))
				))
			;
	  }
	}
}

 
using System;
using System.Linq;
                    
public class Program
{
    public static void Main()
    {
        Console.WriteLine(Plus.Pattern(11));
    }
    
    
    public static class Plus
    {
      public static string Pattern(int n)
      {
            return n < 1 ? "" :
                string.Join("\n", Enumerable.Range(1, n - 1).Select(
                    i =>
                    string.Join("", Enumerable.Repeat(" ", n - 1))
                    +
                    string.Join("", Enumerable.Repeat(i, n).Select(j => j % 10))
                    +
                    string.Join("", Enumerable.Repeat(" ", n - 1))
                )) + "\n" +