public static void Main()
Console.WriteLine("Hello World");
int[] arr = new int[] {2,3,4,5,6,7};
int[] combination = new int[n];
CombinationUtil(arr,combination,0,2,0);
private static void CombinationUtil(int[] arr,int[] combination,int index,int n,int i)
Console.WriteLine(string.Format("i {0}: Index {1}",i,index));
Console.Write(combination[k] + ",");
combination[index] = arr[i];
CombinationUtil(arr,combination,index+1,n,i+1);
CombinationUtil(arr,combination,index,n,i+1);