Number of permutations of [n] avoiding {1324, 2431, 3142}.

Terms

a(0) =1a(1) =1a(2) =2a(3) =6a(4) =21a(5) =76a(6) =275a(7) =989a(8) =3539a(9) =12631a(10) =45066a(11) =161021a(12) =576887a(13) =2074166a(14) =7488003a(15) =27150233a(16) =98878251a(17) =361680595a(18) =1328574654a(19) =4900021037a(20) =18141052047a(21) =67402330234a(22) =251263851255a(23) =939561899651