Combinatorics and Graph Theory · Problem 4.1.1

Systems of Distinct Representatives — David Guichard

Mathematics — Combinatorics · systems-of-distinct-representatives

Problem

How many different systems of distinct representatives are there for

A_1 = \{1, 2\}

A_2 = \{2, 3\}

\ldots

A_n = \{n, 1\}