Number of permutations of length n which avoid the patterns 2314, 3142, 4312.

Terms

a(0) =1a(1) =2a(2) =6a(3) =21a(4) =74a(5) =253a(6) =840a(7) =2728a(8) =8719a(9) =27541a(10) =86221a(11) =268047a(12) =828661a(13) =2550116a(14) =7818174a(15) =23893803a(16) =72831350a(17) =221504503a(18) =672394824a(19) =2037817846a(20) =6167472211a(21) =18643839127a(22) =56301766021a(23) =169874621301a(24) =512161584769