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%I #21 Mar 21 2023 05:16:42
%S 1,1,4,24,288,3240,74160,1970640,55762560,2271628800,118676275200,
%T 5949399456000,389282684313600,31351069535385600,2431871996666112000,
%U 227068393053325824000,25547764411931553792000,2795442523571128983552000,350437557048098924371968000
%N Number of ordered pairs of permutation functions on n elements satisfying f(g(g(g(x)))) = g(g(g(f(x)))).
%C See A239841 for more information and a proof that a(n) is a multiple of n!.
%C a(n) appears be n! * A232218(n).
%H Hiroaki Yamanouchi, <a href="/A255440/b255440.txt">Table of n, a(n) for n = 0..60</a>
%Y Cf. A239841, A232218
%K nonn
%O 0,3
%A _Paul Boddington_, Feb 24 2015
%E a(18) from _Hiroaki Yamanouchi_, Mar 13 2015
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