A157984 - OEIS

%I #16 Aug 01 2015 10:23:22

%S 3,66,1518,36432,910800,23680800,639381600,17902684800,519177859200,

%T 15575335776000,482835409056000,15450733089792000,509874191963136000,

%U 17335722526746624000,606750288436131840000,21843010383700746240000

%N a(n) = n!/(7 * 20!).

%C From calculations for a Witt design:

%C http://www.math.uic.edu/~ronan/Witt_design;

%C a(n)*8!/3! - 48*n!/19!

%t Flatten[Table[If[IntegerQ[48*3!*n!/(8!*19! )], 48*3!*n!/( 8!*19! ), {}], {n, 0, 48}]] (* _Roger L. Bagula_ *)

%t Select[With[{n=48 3!,d=8! 19!},Table[(n  i!)/d,{i,50}]],IntegerQ] (* _Harvey P. Dale_, Jan 05 2011 *)

%t f[n_] := n!/(7 * 20!); Array[f, 10, 21] (* _Robert G. Wilson v_, Jan 05 2011 *)

%K nonn

%O 21,1

%A _Roger L. Bagula_, Mar 10 2009