Enumeration of two particular sets of minimal permutations
Journal of integer sequences, Tome 18 (2015) no. 10
Minimal permutations with $d$ descents and size $d + 2$ have a unique ascent between two sequences of descents. Our aim is the enumeration of two particular sets of these permutations. The first set contains the permutations having $d + 2$ as the top element of the ascent. The permutations in the latter set have 1 as the last element of the first sequence of descents and are the reverse-complement of those in the other set. The main result is that these sets are enumerated by the second-order Eulerian numbers.
@article{JIS_2015__18_10_a7,
author = {Bilotta, Stefano and Grazzini, Elisabetta and Pergola, Elisa},
title = {Enumeration of two particular sets of minimal permutations},
journal = {Journal of integer sequences},
year = {2015},
volume = {18},
number = {10},
zbl = {1328.05006},
language = {en},
url = {http://geodesic.mathdoc.fr/item/JIS_2015__18_10_a7/}
}
Bilotta, Stefano; Grazzini, Elisabetta; Pergola, Elisa. Enumeration of two particular sets of minimal permutations. Journal of integer sequences, Tome 18 (2015) no. 10. http://geodesic.mathdoc.fr/item/JIS_2015__18_10_a7/