This site is supported by donations to The OEIS Foundation.

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A135396 a(n) = product_{d divides n} (n-d)!. 1

%I

%S 1,1,2,12,24,17280,720,87091200,29030400,1755758592000,3628800,

%T 1525930675524002119680000000,479001600,15033074749223731200000,

%U 151533393472175210496000000,2201737050440244933006930739200000000

%N a(n) = product_{d divides n} (n-d)!.

%e n=6, d(i)< 6 are 1;2;3; a(6)= (6-1)! * (6-2)! * (6-3)! = 17280

%p A135396 := proc(n) local dvs ; dvs := numtheory[divisors](n) minus {n} ; mul( (n-i)!,i=dvs) ; end: seq(A135396(n),n=1..30) ; - _R. J. Mathar_, Feb 19 2008

%t Table[Product[(n - Divisors[n][[i]])!, {i,1,Length[Divisors[n]]}], {n, 1, 20}] - _Stefan Steinerberger_, Feb 19 2008

%Y Cf. A000142.

%K easy,nonn

%O 1,3

%A Ctibor O. ZIZKA (ctibor.zizka(AT)seznam.cz), Feb 17 2008

%E Definition simplified by _Stefan Steinerberger_, Feb 19 2008

%E More terms from _R. J. Mathar_ and _Stefan Steinerberger_, Feb 19 2008

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Transforms | Puzzles | Hot | Classics
Recent Additions | More pages | Superseeker | Maintained by The OEIS Foundation Inc.

Content is available under The OEIS End-User License Agreement .