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 A090586 #22 Sep 08 2022 08:45:12
%S A090586 1,2,1,12,8,240,180,1120,8064,725760,604800,79833600,68428800,
%T A090586 830269440,10897286400,2615348736000,2324754432000,711374856192000,
%U A090586 640237370572800,11585247657984000,221172909834240000,102181884343418880000,93666727314800640000
%N A090586 Denominator of Sum/Product of first n numbers.
%C A090586 a(n) = A000142(n)/A069268(n);
%C A090586 a(p-1) = 2*A000142(p-2) for odd primes.
%C A090586 a(n) = A060593((n - 1)/2) for odd n. - _Gregory Gerard Wojnar_, Jun 10 2021
%H A090586 Robert Israel, <a href="/A090586/b090586.txt">Table of n, a(n) for n = 1..451</a>
%p A090586 seq(denom((n+1)/(2*(n-1)!)),n=1..25); # _Robert Israel_, Oct 14 2018
%t A090586 Table[Denominator[(n + 1) / (2 (n - 1)!)], {n, 25}] (* _Vincenzo Librandi_, Oct 15 2018 *)
%o A090586 (Magma) [Denominator(n + 1) / (2*Factorial(n - 1)): n in [1..30]]; // _Vincenzo Librandi_, Oct 15 2018
%Y A090586 Cf. A090585 (numerator), A060593.
%Y A090586 Main diagonal of A093420.
%K A090586 nonn,frac
%O A090586 1,2
%A A090586 _Reinhard Zumkeller_, Dec 03 2003