The number of permutations of length n and tier at most 1, that is, the number of permutations of length n sortable by two passes through a stack where outputting the longest prefix matching the identity permutation is prioritized.
A308726
The number of permutations of length n and tier at most 1, that is, the number of permutations of length n sortable by two passes through a stack where outputting the longest prefix matching the identity permutation is prioritized.
Terms
- a(0) =1a(1) =1a(2) =2a(3) =6a(4) =24a(5) =112a(6) =556a(7) =2811a(8) =14234a(9) =71808a(10) =360568a(11) =1803100a(12) =8988924a(13) =44719588a(14) =222221416a(15) =1103827306a(16) =5484124128a(17) =27265300504a(18) =135695994964a(19) =676228846370
External references
- oeis: A308726