Number of permutations of [n] avoiding {1243, 1324, 4231}.

Terms

a(0) =1a(1) =1a(2) =2a(3) =6a(4) =21a(5) =73a(6) =238a(7) =721a(8) =2044a(9) =5492a(10) =14178a(11) =35610a(12) =87938a(13) =215295a(14) =525787a(15) =1286294a(16) =3160692a(17) =7812235a(18) =19435271a(19) =48669058a(20) =122640467a(21) =310825886a(22) =791852703a(23) =2026485203a(24) =5206520173a(25) =13421671869a(26) =34697109772a(27) =89909564367a(28) =233436502611a(29) =607059621989