Number of permutations avoiding the patterns {2431, 3421, 4231, 4321, 24513, 42513, 34512, 43512}; number of strong sorting class based on 2431.

A111285

Number of permutations avoiding the patterns {2431, 3421, 4231, 4321, 24513, 42513, 34512, 43512}; number of strong sorting class based on 2431.

Terms

    a(0) =1a(1) =1a(2) =2a(3) =6a(4) =20a(5) =66a(6) =216a(7) =706a(8) =2308a(9) =7546a(10) =24672a(11) =80666a(12) =263740a(13) =862306a(14) =2819336a(15) =9217906a(16) =30138228a(17) =98537866a(18) =322172592a(19) =1053353226a(20) =3443970860a(21) =11260168946a(22) =36815469656a(23) =120369313506a(24) =393551182948

External references