Permutations of type $B$ with fixed number of descents and minus signs

Katarzyna Kril, Wojciech Młotkowski

We study three dimensional array of numbers $B(n,k,j)$, $0\le j,k\le n$, where $B(n,k,j)$ is the number of type $B$ permutations of order $n$ with $k$ descents and $j$ minus signs.…