Number of ordered pairs of permutation functions on n elements satisfying f(f(f(x))) = g(f(g(x))).
A239839
Number of ordered pairs of permutation functions on n elements satisfying f(f(f(x))) = g(f(g(x))).
Terms
- a(0) =1a(1) =1a(2) =4a(3) =18a(4) =168a(5) =1560a(6) =20880a(7) =267120a(8) =5080320a(9) =93623040a(10) =2184537600a(11) =49896000000
External references
- oeis: A239839