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A254529
a(n) = n! * (number of mapping patterns on n).
2
1, 1, 6, 42, 456, 5640, 93600, 1728720, 38344320, 948931200, 26555558400, 817935148800, 27735629644800, 1020596255078400, 40642432179148800, 1737890081351424000, 79498734605402112000, 3871319396080840704000, 200017645344178421760000, 10925549584125028909056000
OFFSET
0,3
COMMENTS
a(n) is the number of ordered pairs (p, f) such that p f = f p, where p is a permutation and f is an endofunction.
FORMULA
a(n) = n! * A001372(n). - Joerg Arndt, Feb 01 2015
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Martin Fuller, Feb 01 2015
STATUS
approved