136535455

Appears in sequences

• Number of pairs of functions (f, g) on a set of n elements into itself satisfying f(g(x)) = f(x).at n=7A239761
• Number A(n,k) of pairs of endofunctions f, g on [n] satisfying f(g^k(i)) = f(i) for all i in [n]; square array A(n,k), n>=0, k>=0, read by antidiagonals.at n=43A245910