§ Catalan numbers as popular candidate votes (TODO)

I quite like the latter interpretation, because we really are counting two different things (votes for AA and BB) and then expressing a relationship between them. It also allows us to directly prove that catalan(n) is equal to 1/(n+1)(2nn)1/(n+1) \binom{2n}{n} by reasoning about seqences of votes, called as ballot sequences

§ Ballot sequences

§ References