Number of permutations of length n that avoid the patterns 1243 and 2431.

A165534

Number of permutations of length n that avoid the patterns 1243 and 2431.

Terms

    a(0) =1a(1) =2a(2) =6a(3) =22a(4) =88a(5) =363a(6) =1507a(7) =6241a(8) =25721a(9) =105485a(10) =430767a(11) =1752945a(12) =7113095a(13) =28797292a(14) =116368938a(15) =469531170a(16) =1892133076a(17) =7617145998a(18) =30638026074a(19) =123145086046a(20) =494663313342

External references