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 A156036 #11 Feb 03 2025 22:52:00
%S A156036 0,-1,1,-691,3617,-174611,236364091,-3392780147,7709321041217,
%T A156036 -26315271553053477373,261082718496449122051,-2530297234481911294093,
%U A156036 5609403368997817686249127547,-61628132164268458257532691681,354198989901889536240773677094747,-1215233140483755572040304994079820246041491
%N A156036 Numerators in expansion of log(z^2/(cosh(z)-cos(z))) for exponents that are multiples of 4.
%D A156036 V. Mangulis, Handbook of Series, Academic Press, 1965, p. 76.
%F A156036 log(z^2/(cosh(z)-cos(z))) = Sum_{ n >= 1 } (-1)^n*B_{2n}*(2z^2)^(2n)/((4n)!2n).
%F A156036 a(n) = numerator((-1)^n * zeta(4*n)/(zeta(2*n)*Pi^(2*n))). - _Enrique Pérez Herrero_, Jun 20 2012
%e A156036 log(z^2/(cosh(z)-cos(z))) = -(1/360)*z^4+(1/302400)*z^8-(691/122594472000)*z^12+(3617/333456963840000)*z^16+...
%o A156036 (PARI) my(N=90, z='z+O('z^N), v=apply(numerator, Vec(log(z^2/(cosh(z)-cos(z))), -N))); vector(#v\4, k, v[4*k-2]) \\ _Michel Marcus_, Feb 03 2025
%Y A156036 Cf. A156032.
%K A156036 sign,frac
%O A156036 0,4
%A A156036 _N. J. A. Sloane_, Oct 31 2009
%E A156036 Definition clarified by _Michel Marcus_, Feb 03 2025