.NET Fiddle

CSharp · Console

/Program.cs

using System;
					
public class Program
{
	public static void Main()
	{
		int arraySize = 12;
		
		Console.WriteLine("index\tprevious");
		
		for(int index=1; index<=arraySize; index++)
		{
			var prev = ((index - 1 - arraySize) % arraySize) + arraySize;
				
			Console.WriteLine(index + "\t\t"+prev);
		}
	}
}