4 ms·

Isn’t this result in every introductory combinatorics textbook?

• flyingfences 8y ago
  You're misunderstanding the problem. It's not a question of the number of permutations. It's a question of the total number of episodes that must be watched to have seen all possible permutations.
  • Izkata 8y ago
    Not sure why you're grey; you are correct about why it's not introductory. Overlap between permutations is why it's not as simple as it first sounds. For example, to borrow the wiki example, "121" includes both "12" and "21" permutations.