using System.Text.RegularExpressions;
using System.Collections.Generic;
public static void Main()
var content = "zf3kabxcde224lkzf3mabxc51+crsdtzf3nab=";
var patterns = new HashSet<string>();
for (int i = 0; i < content.Length - patternLength + 1; i++)
var pattern = content.Substring(i, patternLength) ;
var Occurrence = Regex.Matches(content, @"["+ pattern+ @"]{3}").Count;
if (Occurrence > 1 && !patterns.Contains(pattern))
Console.WriteLine(pattern + " : " + Occurrence);