Number of permutations of length n which avoid the patterns 1243, 1342, 4312.

Terms

a(0) =1a(1) =2a(2) =6a(3) =21a(4) =73a(5) =234a(6) =691a(7) =1910a(8) =5019a(9) =12690a(10) =31147a(11) =74694a(12) =175843a(13) =407810a(14) =934179a(15) =2117958a(16) =4759915a(17) =10617234a(18) =23527867a(19) =51839462a(20) =113639955a(21) =247988802a(22) =538968691a(23) =1167065766a(24) =2518680283a(25) =5419041554a(26) =11626611531a(27) =24880612230