Number of permutations of length n which avoid the patterns 1342, 3214, 4213.

Terms

a(0) =1a(1) =2a(2) =6a(3) =21a(4) =73a(5) =239a(6) =738a(7) =2178a(8) =6220a(9) =17351a(10) =47595a(11) =128985a(12) =346492a(13) =924788a(14) =2456502a(15) =6502017a(16) =17164189a(17) =45219875a(18) =118954134a(19) =312559974a(20) =820560736a(21) =2152792187a(22) =5645155791a(23) =14797355181a(24) =38776269808a(25) =101590174424a(26) =266111693898a(27) =696979788213