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 A255506 #17 Sep 08 2022 08:46:11
%S A255506 2,12,120,504,1440,3168,3931200,8640,41126400,579156480,2395008000,
%T A255506 1001548800,2615348736000,5748019200,21670032384000,7491404919398400,
%U A255506 21341245685760000,251073478656000,24574743184592240640000,76828484468736000,65834328341259878400000
%N A255506 Denominator of Bernoulli(2n)/(2n!).
%H A255506 MathOverflow, <a href="http://mathoverflow.net/questions/157115">What can be said about a function given its asymptotic expansion?</a>
%e A255506 The sequence Bernoulli(2n)/(2n!) (n >= 0) begins 1/2, 1/12, -1/120, 1/504, -1/1440, 1/3168, -691/3931200, 1/8640, -3617/41126400, ...
%t A255506 Table[Denominator[BernoulliB[2 n]/(2 n!)], {n, 0, 25}]
%o A255506 (Magma) [Denominator(Bernoulli(2*n)/(2*Factorial(n))): n in [0..25]]; // _Vincenzo Librandi_, Feb 24 2015
%o A255506 (PARI) a(n) = denominator(bernfrac(2*n)/(2*n!)); \\ _Michel Marcus_, Feb 24 2015
%o A255506 (Sage) [denominator(bernoulli(2*n)/(2*factorial(n))) for n in (0..25)] # _Bruno Berselli_, Feb 24 2015
%Y A255506 Cf. A255505 (numerator).
%K A255506 nonn,frac
%O A255506 0,1
%A A255506 _Jean-François Alcover_, Feb 24 2015