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%I #8 Jul 16 2014 18:59:48
%S 1,1,10,231,9688,603445,52284816,5951141035
%N Number of pairs of functions f, g from a size n set into itself satisfying f(f(x)) = f(g(f(x))).
%p s:= proc(n, i) option remember; `if`(i=0, [[]],
%p map(x-> seq([j, x[]], j=1..n), s(n, i-1)))
%p end:
%p a:= proc(n) local l; l:= s(n$2);
%p add(add(`if`([seq(evalb(f[f[i]]=f[g[f[i]]]),
%p i=1..n)]=[true$n], 1, 0), g=l), f=l)
%p end:
%p seq(a(n), n=0..5); # _Alois P. Heinz_, Jul 16 2014
%Y Cf. A181162, A239769, A239773.
%K nonn,more
%O 0,3
%A _Chad Brewbaker_, Mar 26 2014
%E a(6)-a(7) from _Giovanni Resta_, Mar 28 2014
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