This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A163089 #5 Jul 26 2013 04:46:37
%S A163089 1,1,1,1,2,4,3,36,48,96,240,14400,2160,518400,90720,141120,1935360,
%T A163089 1625702400,870912,131681894400,145152000,15676416000,287400960000,
%U A163089 1593350922240000,14780620800,7648084426752000,1614043791360000
%N A163089 n! / (Product{k|n} k$). Here '$' denotes the swinging factorial function (A056040).
%H A163089 Peter Luschny, <a href="http://www.luschny.de/math/primes/SwingingPrimes.html"> Swinging Primes.</a>
%p A163089 a := n -> n! / A163087(n):
%t A163089 sf[n_] := With[{f = Floor[n/2]}, Pochhammer[f+1, n-f]/f!]; a[0] = 1; a[n_] := n!/Product[sf[k], {k, Divisors[n]}]; Table[a[n], {n, 0, 26}] (* _Jean-François Alcover_, Jul 26 2013 *)
%Y A163089 Cf. A163087, A163088.
%K A163089 nonn
%O A163089 0,5
%A A163089 _Peter Luschny_, Jul 21 2009