How can i solve this ? :(

How many ways to make a number n, using k number of coins from an array of coins?

where 1 <= n <= 10 ^ 9 and 1 <= k <= 10

for example if the array is A[1, 2, 3, 5, 8, 13] and k = 4 and n = 13 . Answer will be 4

as, 1 + 1 + 3 + 8 = 13, 1 + 2 + 2 + 8 = 13, 1 + 2 + 5 + 5 = 13, 2 + 3 + 3 + 5 = 13

Thanks in advance :)