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 A190357 #29 Oct 01 2022 00:01:02
%S A190357 0,4,7,3,5,7,6,3,2,7,1,5,3,2,4,4,5,7,1,1,2,2,4,1,0,7,3,5,8,0,5,4,4,7,
%T A190357 2,2,1,9,1,2,8,2,4,5,0,6,5,5,5,0,6,9,0,2,3,0,8,7,8,1,9,3,6,2,1,1,6,5,
%U A190357 3,7,5,8,0,7,5,5,2,9,1,1,7,6,1,7,5,8,1,4,5,2,1,4,8,7,5,6,3,2,4,7,7
%N A190357 Decimal expansion of 1/4 - 2/Pi^2.
%C A190357 Constant given on p. 1 of Schlage-Puchta.
%H A190357 G. C. Greubel, <a href="/A190357/b190357.txt">Table of n, a(n) for n = 0..10000</a>
%H A190357 Jan-Christoph Schlage-Puchta, <a href="http://arxiv.org/abs/1105.1305">Sumsets avoiding squarefree integers</a>, arXiv:1105.1305 [math.NT], May 06 2011.
%H A190357 <a href="/index/Tra#transcendental">Index entries for transcendental numbers</a>
%F A190357 Equals (1/4) - (2/Pi^2).
%e A190357 0.047357632715324457112241...
%t A190357 Join[{0}, RealDigits[(1/4) - (2/Pi^2), 10, 100][[1]]] (* _G. C. Greubel_, Apr 05 2018 *)
%o A190357 (PARI) (1/4) - (2/Pi^2) \\ _G. C. Greubel_, Apr 05 2018
%o A190357 (Magma) R:=RealField(100); [(1/4) - (2/Pi(R)^2)]; // _G. C. Greubel_, Apr 05 2018
%Y A190357 Cf. A005117, A010716 (1/18), A059956 (6/Pi^2).
%K A190357 nonn,easy,cons
%O A190357 0,2
%A A190357 _Jonathan Vos Post_, May 09 2011