A combinatorial proof of the log-concavity of a famous sequence counting permutations
The author proves combinatorially that the sequence \((i(n,k))_{0\leq k\leq{n\choose 2}}\) of the numbers of permutations of length \(n\) with \(k\) inversions is log-concave for any \(n\).
scientific article; zbMATH DE number 2161260