Klazar, Martin. “On Growth Rates of Permutations, Set Partitions, Ordered Graphs and Other Objects”. The Electronic Journal of Combinatorics 15, no. 1 (May 31, 2008): R75. Accessed March 27, 2026. https://www.combinatorics.org/ojs/index.php/eljc/article/view/v15i1r75.