Number of permutations of [n] avoiding {1324, 3142, 4231}.

Terms

a(0) =1a(1) =1a(2) =2a(3) =6a(4) =21a(5) =73a(6) =242a(7) =762a(8) =2290a(9) =6610a(10) =18434a(11) =49922a(12) =131842a(13) =340738a(14) =864258a(15) =2156546a(16) =5304322a(17) =12881922a(18) =30932994a(19) =73531394a(20) =173211650a(21) =404684802a(22) =938475522a(23) =2161639426a(24) =4948230146a(25) =11262754818a(26) =25501368322a(27) =57461964802a(28) =128899350530a(29) =287947358210