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A034841 (n^2)! / (n!)^n. 11
1, 6, 1680, 63063000, 623360743125120, 2670177736637149247308800, 7363615666157189603982585462030336000, 18165723931630806756964027928179555634194028454000000, 53130688706387569792052442448845648519471103327391407016237760000000000 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

The number of arrangements of 1,2,...,n*n in an n X n matrix such that each row is increasing. - Ahmed Fares (ahmedfares(AT)my-deja.com), Jul 12 2001

a(n) == 0 mod (n!). In fact (n^2)! == 0 mod (n!)^n by elementary combinatorics, a better result is (n^2)! == 0 ((mod(n!)^(n+1)). - Amarnath Murthy, Jul 13 2005

a(n) is also the number of lattice paths from {n}^n to {0}^n using steps that decrement one component by 1. a(2) = 6: [(2,2), (1,2), (0,2), (0,1), (0,0)], [(2,2), (1,2), (1,1), (0,1), (0,0)], [(2,2), (1,2), (1,1), (1,0), (0,0)], [(2,2), (2,1), (1,1), (0,1), (0,0)], [(2,2), (2,1), (1,1), (1,0), (0,0)], [(2,2), (2,1), (2,0), (1,0), (0,0)]. - Alois P. Heinz, May 06 2013

Given n^2 distinguishable balls and n distinguishable urns, a(n) = the number of ways to place n balls in the i_th urn for all 1 <= i <= n, where n = n_1 + n_2 + ... + n_n. - Ross La Haye, Dec 28 2013

LINKS

Alois P. Heinz, Table of n, a(n) for n = 1..20

FORMULA

Using a higher order version of Stirling's formula (the "standard" formula appears in A000142) we have the asymptotic expression: a(n) ~ sqrt(2*pi) * e^(-1/12) * n^(n^2 - n/2 + 1) / (2*pi)^(n/2). - Dan Fux (dan.fux(AT)OpenGaia.com or danfux(AT)OpenGaia.com), Apr 13 2001

MAPLE

a:= n-> (n^2)! / (n!)^n:

seq(a(n), n=1..10);  # Alois P. Heinz, Jul 24 2012

CROSSREFS

Cf. A000142, A039622, A229050, A229050.

Diagonal of A089759, A187783. - Alois P. Heinz, Jan 23 2013

Sequence in context: A216934 A160226 A209609 * A149187 A221627 A160301

Adjacent sequences:  A034838 A034839 A034840 * A034842 A034843 A034844

KEYWORD

nonn

AUTHOR

Erich Friedman

STATUS

approved

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Last modified September 20 18:16 EDT 2014. Contains 247018 sequences.