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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 (list; graph; refs; listen; history; text; internal format)
 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. LINKS Alois P. Heinz, Table of n, a(n) for n = 0..382 Math Overflow, What is the probability two random maps on n symbols commute?, 2013. FORMULA a(n) = n! * A001372(n). - Joerg Arndt, Feb 01 2015 CROSSREFS Cf. A001372, A053529, A181162. Sequence in context: A245248 A197712 A306173 * A098461 A284161 A034662 Adjacent sequences:  A254526 A254527 A254528 * A254530 A254531 A254532 KEYWORD nonn,easy AUTHOR Martin Fuller, Feb 01 2015 STATUS approved

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Last modified January 22 07:31 EST 2022. Contains 350481 sequences. (Running on oeis4.)