%I #15 Mar 12 2015 12:18:26
%S 1,1,1,2,4,5,9,17,26,46,87,137,246,474,791,1420,2783,4839,8806,17361,
%T 31252,57613,114497,211496,395637,791597,1495016,2834242,5710510,
%U 10986325,21101677,42796060,83674582,162695172,332141014,658589710,1295551257,2661881254
%N 1/n! times the number of ordered pairs of permutation functions f,g on n elements where f(f(x)) = g(f(g(x))).
%C The fact that A239837(n) is a multiple of n! follows from a general result in group theory due to Solomon.
%H Hiroaki Yamanouchi, <a href="/A255515/b255515.txt">Table of n, a(n) for n = 0..60</a>
%H L. Solomon, <a href="http://dx.doi.org/10.1007/BF01899292">The solutions of equations in groups</a>, Arch. Math., V.20. no.3, (1969) 241-247.
%F a(n) = A239837(n)/n!.
%Y Cf. A239837.
%K nonn
%O 0,4
%A _Paul Boddington_, Feb 24 2015
%E a(14)-a(37) from _Hiroaki Yamanouchi_, Mar 12 2015