In how many ways can a positive integer n be broken into a sum of k positive integers ? ( While representing the number as a sum the order in which the addends are arranged for each of the ways is not taken into consideration)

I know that we denote the number of ways to do this as and I tried an inductive approach to the problem , i.e, I was able to figure out that ,

But I cant seem to figure out and so on....And I need a closed-form solution, not recurrence relations..So, please help . Thanks in advance .