Number of permutations of [n] avoiding {4231, 1324, 1234}.

Terms

a(0) =1a(1) =1a(2) =2a(3) =6a(4) =21a(5) =73a(6) =238a(7) =714a(8) =1962a(9) =4957a(10) =11604a(11) =25390a(12) =52361a(13) =102533a(14) =191868a(15) =344970a(16) =598682a(17) =1006793a(18) =1646094a(19) =2624054a(20) =4088421a(21) =6239089a(22) =9342610a(23) =13749770a(24) =19916690a(25) =28429957a(26) =40036336a(27) =55677662a(28) =76531561a(29) =104058701