A New Upper Bound for 1324-Avoiding Permutations

@article{Bna2014ANU,
  title={A New Upper Bound for 1324-Avoiding Permutations},
  author={Mikl{\'o}s B{\'o}na},
  journal={Combinatorics, Probability & Computing},
  year={2014},
  volume={23},
  pages={717-724}
}
We prove that the number of 1324-avoiding permutations of length n is less than (7 + 4 √ 3). 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.