Alright. I found the answer to (a) to be 10626 and am quite confident I am correct, and (c) is just that answer*(20!).
Now I am stuck on part (b). Any hints would be appreciated.
Homework Statement
45.) Twenty different books are to be put on five book shelves, each of which holds at least twenty books.
a) How many different arrangements are there if you only care about the number of books on the shelves (and not which book is where)?
b) How many different arrangements...