Number of permutations of length n which avoid the patterns 2341, 4123, 4132.

Terms

a(0) =1a(1) =2a(2) =6a(3) =21a(4) =74a(5) =249a(6) =804a(7) =2540a(8) =7977a(9) =25106a(10) =79327a(11) =251328a(12) =797094a(13) =2527977a(14) =8014590a(15) =25401277a(16) =80494292a(17) =255072244a(18) =808301057a(19) =2561517150a(20) =8117640043a(21) =25725562136a(22) =81526606470a(23) =258364283985a(24) =818775016906