factorial ncr + unique list, C#

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//Rextester.Program.Main is the entry point for your code. Don't change it.
//Compiler version 4.0.30319.17929 for Microsoft (R) .NET Framework 4.5

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text.RegularExpressions;

namespace Rextester
{
    public class Program
    {
        public static void Main(string[] args)
        {
            //Your code goes here
            int t0,t1,t2,t3;
            int[] t = new int[4];
            t[0]=1;
            t[1]=2;
            t[2]=3;
            t[3]=4/2;
            
            List<int> num = new List<int>(t);
            //Console.WriteLine(nCr(12,8));
            
            Console.WriteLine(Unique(num));
        }
        
        public static bool Unique(List<int> t){
        
            int count = 0;
            for (int i=0; i<t.Count()-1; i++){ 
                for (int j=i+1; j<t.Count(); j++) { 
                    //Console.WriteLine(i + " " + j);
                    
                    if (!t[i].Equals(t[j])){
                    
                        count++;
                    }
                       
                }
            }
            if (count.Equals(nCr(t.Count(),2))) {
                
                return true;
            }
            else return false;
        }
        
        public static int nCr(int n, int r) {
        
            return (Factorial(n)/Factorial(r))/Factorial(n-r);
        }
        
        public static int Factorial(int n) {
            
            if (n>0) {
                for (int i=n-1; i>1; i--) {

n = n*i;
                }

return n;
            }
            
            else if (n<0) throw new ArgumentOutOfRangeException("n","n should be non-zero");
                
            else return 1;
            
            
                  
        }
            
            
        
    }
}

Show compiler warnings [ + ] Show input
Compilation time: 0,25 sec, absolute running time: 0,14 sec, cpu time: 0,12 sec, average memory usage: 13 Mb, average nr of threads: 3, absolute service time: 0,42 sec