A255440 Number of ordered pairs of permutation functions on n elements satisfying f(g(g(g(x)))) = g(g(g(f(x)))).

1, 1, 4, 24, 288, 3240, 74160, 1970640, 55762560, 2271628800, 118676275200, 5949399456000, 389282684313600, 31351069535385600, 2431871996666112000, 227068393053325824000, 25547764411931553792000, 2795442523571128983552000, 350437557048098924371968000

Offset: 0

Author

Paul Boddington, Feb 24 2015

Keywords

• nonn

Comments

See A239841 for more information and a proof that a(n) is a multiple of n!.

a(n) appears be n! * A232218(n).

Links

• Hiroaki Yamanouchi, Table of n, a(n) for n = 0..60

Crossrefs

Cf. A239841, A232218

Extensions

a(18) from Hiroaki Yamanouchi, Mar 13 2015