A New Upper Bound for 1324-Avoiding Permutations. (September 2014) - BÓNA, MIKLÓS
Abstract We prove that the number of 1324-avoiding permutations of length n is less than $(7+4\sqrt{3})^n$ . The novelty of our method is that we injectively encode such permutations by a pair of words of length n over a finite alphabet that avoid a given factor.