%I
%S 1,1,12,504,43680,6375600,1402410240,432938943360,178462987637760,
%T 94670977328928000,62815650955529472000,50963773003971232204800,
%U 49633807532904958383820800,57141374006987657125324185600,76763145767753986733306290176000,119005648371962652004288345681920000
%N a(n) = (n^2)! / (n^2n)! = number of ways of placing n labeled balls into n^2 labeled boxes with at most one ball in each box.
%t Table[(n^2)!/(n^2n)!,{n,0,20}] (* _Harvey P. Dale_, Aug 10 2017 *)
%o (Python)
%o import math
%o for n in range(20):
%o print str(math.factorial(n*n)/math.factorial(n*nn))+',',
%Y Cf. A014062.
%K nonn,easy
%O 0,3
%A _Alex Ratushnyak_, Jun 29 2013
