Number of permutations of [n] avoiding {2341, 3142, 4123}.

Terms

a(0) =1a(1) =1a(2) =2a(3) =6a(4) =21a(5) =74a(6) =253a(7) =843a(8) =2772a(9) =9080a(10) =29759a(11) =97686a(12) =321033a(13) =1055596a(14) =3471365a(15) =11415280a(16) =37535830a(17) =123420905a(18) =405812530a(19) =1334326344a(20) =4387329985a(21) =14425801573a(22) =47432972821a(23) =155962779313a(24) =512816020062