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 A033470 #20 Jul 08 2025 19:52:39
%S A033470 1,-1,13,-121,1093,-49205,61203943,-5580127,25949996501,
%T A033470 -2832495743227,101471818419863,-4469253897850313,
%U A033470 11126033443528968583,-3623473373642099263,90551915146257709805297,-295654219044074800178128205
%N A033470 Numerator of Bernoulli(2n,1/3).
%H A033470 <a href="/index/Be#Bernoulli">Index entries for sequences related to Bernoulli numbers.</a>
%p A033470 with(numtheory): seq(numer(bernoulli(2*n, 1/3)), n=0..20);
%t A033470 Table[Numerator @ BernoulliB[2*n, 1/3], {n, 0, 15}] (* _Amiram Eldar_, Sep 16 2020 *)
%o A033470 (PARI) a(n) = numerator(subst(bernpol(2*n), x, 1/3)); \\ _Michel Marcus_, Sep 16 2020
%Y A033470 Cf. A033471 (denominators).
%K A033470 sign,frac
%O A033470 0,3
%A A033470 _N. J. A. Sloane_