I need to solve the problem,
How many sequence of integers ($j_1 , j_2 , . . . , j_k$) are there such that $0 ≤ j_1 ≤ j_2 ≤ . . . ≤ j_k ≤ n$?
I've been given a hint,
(Hint: Reduce the problem to $0 < j_1 < j_2 < . . . < j_k < n)$.
The answer will be in terms of k and n.
First of all, I don't see how to reduce the problem, or what to do when it's reduced. Secondly, I feel bad about not having much to show for my effort, but I have been working on this problem for some time and I'm not sure where to start. If someone could give me a general outline of what method to use or something like that, I'd appreciate it.