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A239753
Number of pairs of functions (f,g) on a set of n elements into itself satisfying f(x) = g(f(g(x))).
0
1, 1, 8, 87, 1312, 24685, 564336, 15168811
OFFSET
0,3
FORMULA
a(n) <= n^2n. - Charles R Greathouse IV, Mar 26 2014
CROSSREFS
Sequence in context: A225613 A358982 A243922 * A375542 A246512 A366233
KEYWORD
nonn,more
AUTHOR
Chad Brewbaker, Mar 26 2014
EXTENSIONS
a(6)-a(7) from Giovanni Resta, Mar 28 2014
STATUS
approved