Bóna M. A Combinatorial Proof of the Log-Concavity of a Famous Sequence Counting Permutations. Electron. J. Combin. [Internet]. 2005Jan.24 [cited 2026Mar.15];11(2):N2. Available from: https://www.combinatorics.org/ojs/index.php/eljc/article/view/v11i2n2