Number of ordered pairs of permutation functions on n elements satisfying f(g(g(g(x)))) = g(g(g(f(x)))).

A255440

Number of ordered pairs of permutation functions on n elements satisfying f(g(g(g(x)))) = g(g(g(f(x)))).

Terms

    a(0) =1a(1) =1a(2) =4a(3) =24a(4) =288a(5) =3240a(6) =74160a(7) =1970640a(8) =55762560a(9) =2271628800a(10) =118676275200

External references