Number of permutations of length n which avoid the patterns 3412, 4123, 4321.

A116737

Number of permutations of length n which avoid the patterns 3412, 4123, 4321.

Terms

    a(0) =1a(1) =2a(2) =6a(3) =21a(4) =72a(5) =246a(6) =845a(7) =2901a(8) =9955a(9) =34165a(10) =117254a(11) =402409a(12) =1381046a(13) =4739681a(14) =16266344a(15) =55825262a(16) =191589456a(17) =657525254a(18) =2256593172a(19) =7744512803a(20) =26578773396a(21) =91216996231a(22) =313052083987

External references