OFFSET
0,4
COMMENTS
Number of permutations of the multiset of prime factors of n!.
LINKS
Wikipedia, Multinomial theorem
EXAMPLE
The a(5) = 20 permutations of {2,2,2,3,5}:
(22235) (32225) (52223)
(22253) (32252) (52232)
(22325) (32522) (52322)
(22352) (35222) (53222)
(22523)
(22532)
(23225)
(23252)
(23522)
(25223)
(25232)
(25322)
MATHEMATICA
Table[Multinomial@@Last/@FactorInteger[n!], {n, 0, 15}]
CROSSREFS
KEYWORD
nonn
AUTHOR
Gus Wiseman, May 12 2019
STATUS
approved