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 A255505 #16 Sep 08 2022 08:46:11
%S A255505 1,1,-1,1,-1,1,-691,1,-3617,43867,-174611,77683,-236364091,657931,
%T A255505 -3392780147,1723168255201,-7709321041217,151628697551,
%U A255505 -26315271553053477373,154210205991661,-261082718496449122051,1520097643918070802691
%N A255505 Numerator of Bernoulli(2n)/(2n!).
%C A255505 This sequence is different from A001067 or A046968 or A141590, at least at a(52).
%H A255505 MathOverflow, <a href="http://mathoverflow.net/questions/157115">What can be said about a function given its asymptotic expansion?</a>
%e A255505 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 A255505 Table[Numerator[BernoulliB[2 n]/(2 n!)], {n, 0, 25}]
%o A255505 (Magma) [Numerator(Bernoulli(2*n)/(2*Factorial(n))):n in [0..30]]; // _Vincenzo Librandi_, Feb 24 2015
%o A255505 (PARI) a(n) = numerator(bernfrac(2*n)/(2*n!)); \\ _Michel Marcus_, Feb 24 2015
%o A255505 (Sage) [numerator(bernoulli(2*n)/(2*factorial(n))) for n in (0..25)] # _Bruno Berselli_, Feb 24 2015
%Y A255505 Cf. A000367, A001067, A046968, A141590, A255506 (denominator).
%K A255505 sign,frac
%O A255505 0,7
%A A255505 _Jean-François Alcover_, Feb 24 2015