Triangle read by rows: T(n,k) is the number of 3-stack-sortable permutations of [n] with k descents (0 <= k <= n-1).

A324916

Triangle read by rows: T(n,k) is the number of 3-stack-sortable permutations of [n] with k descents (0 <= k <= n-1).

Terms

    a(0) =1a(1) =1a(2) =1a(3) =1a(4) =4a(5) =1a(6) =1a(7) =11a(8) =11a(9) =1a(10) =1a(11) =25a(12) =62a(13) =25a(14) =1a(15) =1a(16) =50a(17) =252a(18) =252a(19) =50a(20) =1a(21) =1a(22) =91a(23) =833a(24) =1644a(25) =833a(26) =91a(27) =1a(28) =1a(29) =154

External references