OFFSET
0,3
COMMENTS
From Tilman Piesk, Oct 30 2014: (Start)
Column 9 of A187783.
Number of permutations of a multiset that contains n different elements, each occurring 9 times.
Or in other words (the former title of this sequence):
Number of 9*n X n 0..1 arrays with row sums 1 and column sums 9.
(End)
LINKS
Tilman Piesk, Table of n, a(n) for n = 0..54 (first 11 terms from R. H. Hardin)
FORMULA
a(n) = (9n)!/(9!^n).
EXAMPLE
a(3) = (9*3)!/(9!^3) = 227873431500 is the number of permutations of a multiset that contains 3 different elements, each occurring 9 times, e.g., {1,1,1,1,1,1,1,1,1,2,2,2,2,2,2,2,2,2,3,3,3,3,3,3,3,3,3}.
MAPLE
MATHEMATICA
Table[(9 n)! / (362880^n), {n, 0, 10}] (* Vincenzo Librandi, Nov 01 2014 *)
PROG
(Magma) [Factorial(9*n)/(362880^n): n in [0..20]]; // Vincenzo Librandi, Nov 01 2014
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
R. H. Hardin, Feb 06 2010
EXTENSIONS
Name changed by Tilman Piesk, Oct 30 2014
STATUS
approved