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%I #16 Mar 12 2015 12:17:58
%S 1,1,2,12,96,600,6480,85680,1048320,16692480,315705600,5468601600,
%T 117834393600,2951607859200,68958028339200,1856897602560000,
%U 58228124258304000,1721171464556544000,56379302852640768000,2111880588197732352000,76033053559536353280000
%N Number of ordered pairs of permutation functions on n elements satisfying f(f(x)) = g(f(g(x))).
%H Hiroaki Yamanouchi, <a href="/A239837/b239837.txt">Table of n, a(n) for n = 0..60</a>
%Y Cf. A000012, A000085, A000142, A088311, A053529, A001044.
%K nonn
%O 0,3
%A _Chad Brewbaker_, Mar 27 2014
%E a(8)-a(9) from _Giovanni Resta_, Mar 27 2014
%E a(10)-a(13) from _Paul Boddington_, Feb 23 2015
%E a(14)-a(20) from _Hiroaki Yamanouchi_, Mar 12 2015
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