Just wondering how to get a generating function to tell me the total number of combinations that add up to a particular number as follows.
1. 4 numbers added together that have a total of say 20.
2. The 4 numbers used must all be different and must be contained between say 1 and 30 inclusive.
a+b+c+d = 20
1+2+3+14 = 20
cannot have 1+1+2+17 = 20
Not sure how to do this? Any ideas?