Egge ES, Mansour T. Permutations Which Avoid 1243 and 2143, Continued Fractions, and Chebyshev Polynomials. Electron. J. Combin. [Internet]. 2003Jan.22 [cited 2026Mar.30];9(2):R7. Available from: https://www.combinatorics.org/ojs/index.php/eljc/article/view/v9i2r7