Number of permutations of [n] avoiding {1324, 2341, 2413}.

Terms

a(0) =1a(1) =1a(2) =2a(3) =6a(4) =21a(5) =74a(6) =255a(7) =857a(8) =2815a(9) =9063a(10) =28677a(11) =89389a(12) =275034a(13) =836689a(14) =2520128a(15) =7524372a(16) =22291317a(17) =65581700a(18) =191743857a(19) =557466281a(20) =1612517029a(21) =4642784877a(22) =13311163941a(23) =38016320047a(24) =108187223460a(25) =306869427745a(26) =867780176654