Как сделать все возможные комбинации? - C#

int[] mas = new int[]{2,3,4,5,6};
var combinations =
 from a in mas
 from b in mas
 from c in mas
 from d in mas
 where
 a != b && a != c && a != d
 && b != c && b != d
 && c != d
 select Tuple.Create(a,b,c,d);
foreach (Tuple<int,int,int,int> t in combinations)
{
 Console.WriteLine("{0}, {1}, {2}, {3}", t.Item1, t.Item2, t.Item3, t.Item4);
}