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 A157780 #10 Jan 01 2023 09:05:07
%S A157780 1,1,12,1,240,1,1344,1,3840,1,33792,1,5591040,1,49152,1,16711680,1,
%T A157780 104595456,1,173015040,1,289406976,1,22900899840,1,201326592,1,
%U A157780 116769423360,1,7689065201664,1,1095216660480,1,51539607552,1
%N A157780 Denominator of Bernoulli(n, 1/2).
%C A157780 Included for completeness, A033469 is the official version of this sequence.
%H A157780 Vincenzo Librandi, <a href="/A157780/b157780.txt">Table of n, a(n) for n = 0..250</a>
%F A157780 a(n) = denominator(-(1-2^(1-n))*Bernoulli(n)). - _Fabián Pereyra_, Dec 31 2022
%t A157780 Table[Denominator[BernoulliB[n, 1/2]], {n, 0, 50}] (* _Vincenzo Librandi_, Mar 19 2014 *)
%Y A157780 For numerators see A157779.
%K A157780 nonn,frac
%O A157780 0,3
%A A157780 _N. J. A. Sloane_, Nov 08 2009