Mixed r-stirling numbers of the second kind

Daniel Yaqubi, Madjid Mirzavaziri, Yasin Saeednezhad

The Stirling number of the second kind $\left\{\genfrac{}{}{0ex}{}{n}{k}\right\}$ counts the number of ways to partition a set of $n$ labeled balls into $k$ non-empty unlabeled cells. As an extension of this, we…