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 A269443 #11 Feb 16 2025 08:33:30
%S A269443 0,1,4,1,1,1,2,1,1,1,1,3,2,2,4,1,1,1,1,1,1,4,1,6,3,7,1,7,3,3,2,4,2,2,
%T A269443 1,1,2,1,1,3,2,1,5,1,3,1,2,1,1,13,40,1,1,1,48,211,4,91,1,16,9,1,10,8,
%U A269443 2,4,1,2,3,2,1,1,13,3,1,2,2,1,3,1,18,2,1,1,1,5,3,7,1,1,21,1,6,4,1,1,2,1,3,2
%N A269443 Continued fraction expansion of the Dirichlet eta function at 2.
%C A269443 Continued fraction expansion of Sum_{k>=1} (-1)^(k-1)/k^2 = Zeta(2)/2 = Pi^2/12 = 0.8224670334241132182362...
%H A269443 OEIS Wiki, <a href="https://oeis.org/wiki/Zeta_functions#Euler.27s_alternating_zeta_function">Euler's alternating zeta function</a>
%H A269443 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/DirichletEtaFunction.html">Dirichlet Eta Function</a>
%H A269443 Wikipedia, <a href="http://en.wikipedia.org/wiki/Dirichlet_eta_function">Dirichlet Eta Function</a>
%H A269443 <a href="/index/Con#confC">Index entries for continued fractions for constants</a>
%e A269443 1/1^2 - 1/2^2 + 1/3^2 - 1/4^2 + 1/5^2 - 1/6^2 +... = 1/(1 + 1/(4 + 1/(1 + 1/(1 + 1/(1 + 1/(2 + 1/...)))))).
%t A269443 ContinuedFraction[Pi^2/12, 100]
%o A269443 (PARI) contfrac(Pi^2/12) \\ _Michel Marcus_, Feb 26 2016
%Y A269443 Cf. A013679, A072691.
%K A269443 nonn,cofr
%O A269443 0,3
%A A269443 _Ilya Gutkovskiy_, Feb 26 2016