Journal of the
Korean Mathematical Society JKMS

An $(n_1,n_2,\dots,n_k)$-colored permutation is a permutation of $n_1+n_2+\dots+n_k$ in which $1,2,\dots,n_1$ have color $1$, and $n_1+1$, $n_1+2$, $\dots,n_1+n_2$ have color $2$, and so on. We give a bijective proof of Steinhardt's result: the number of colored permutations with no monochromatic cycles is equal to the number of permutations with no fixed points after reordering the first $n_1$ elements, the next $n_2$ element, and so on, in ascending order. We then find the generating function for colored permutations with no monochromatic cycles. As an application we give a new proof of the well known generating function for colored permutations with no fixed colors, also known as multi-derangements.

Keywords: colored permutation, multi-derangement, exponential formula

MSC numbers: 05A05, 05A15, 05A19