The set of forbidden pattern is

                             {[1, 2, 3], [1, 3, 2]}

                         This is the (RIGOROUS) scheme

   [{[1, 2], [2, 1]}, {[], [1]}, table([       , table([                   ,
                                     [1, 2] = 2      [1] = {[1, 2], [2, 1]}
                                     [2, 1] = 1      [] = {[1]}
                                 ])              ])

       table([            ]
           [1] = {}
           [] = {}
           [1, 2] = {1, 2}
           [2, 1] = {}
       ])

                              This is the sequence

   [1, 1, 2, 4, 8, 16, 32, 64, 128, 256, 512, 1024, 2048, 4096, 8192, 16384,

       32768, 65536, 131072, 262144, 524288]

                    This is the (Semi-Rigorous) Recurrence

                             - (- 2 + N) (- 1 + n)