A239836 Number of ordered pairs of permutation functions f,g on a size n set where f(g(g(x))) = g(f(f(x))).
1, 1, 2, 6, 48, 360, 2880, 20160, 241920, 3265920, 47174400, 678585600, 12933043200, 193037644800, 3661488230400, 74537438976000, 1736591560704000, 36991492521984000
Offset: 0
Formula
a(n) = A255525(n) * n!.
Extensions
a(8)-a(9) from Giovanni Resta, Mar 27 2014
a(10)-a(16) from Max Alekseyev, Jan 29 2025