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 A093753 #35 Feb 16 2025 08:32:53
%S A093753 1,7,2,8,2,7,4,5,0,9,7,4,5,8,2,0,5,0,1,9,5,7,4,0,9,3,4,1,8,6,4,2,2,8,
%T A093753 6,2,8,9,5,1,4,2,4,7,5,9,0,2,9,7,1,0,1,2,8,9,6,3,9,9,5,0,6,9,7,5,3,9,
%U A093753 1,2,5,4,8,1,2,1,1,6,2,2,3,7,3,5,8,0,7,9,6,7,8,7,9,2,1,6,4,0,6,2,8,0
%N A093753 Decimal expansion of (-2*Catalan + Pi*log(2))/2.
%D A093753 Steven R. Finch, Mathematical Constants, Encyclopedia of Mathematics and its Applications, vol. 94, Cambridge University Press, 2003, Section 1.7.2, p. 55.
%H A093753 Su Hu, Min-soo Kim, <a href="https://arxiv.org/abs/2201.01124">Euler's integral, multiple cosine function and zeta values</a>, arXiv:2201.011247 (2023), Example 2.5.
%H A093753 Michael I. Shamos, <a href="http://euro.ecom.cmu.edu/people/faculty/mshamos/cat.pdf">A catalog of the real numbers</a>, (2007). See p. 215.
%H A093753 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/RadialIntegrals.html">Radial Integrals</a>.
%F A093753 Equals Integral_{x=0..1; y=0..1} [x^2+y^2>1]/(x^2+y^2) where [] is the Iverson bracket.
%F A093753 Equals Integral_{0..1} log(1+x^2)/(1+x^2) dx. - _Jean-François Alcover_, Sep 22 2014
%F A093753 Equals Sum_{k>=1} (-1)^(k+1) * H(k)/(2*k+1), where H(k) = A001008(k)/A002805(k) is the k-th harmonic number. - _Amiram Eldar_, Jul 22 2020
%e A093753 0.17282745097458205019574...
%p A093753 evalf(-Catalan+Pi*log(2)/2) ; # _R. J. Mathar_, Apr 01 2010
%t A093753 First[RealDigits[Pi*Log[2]/2 - Catalan, 10, 100]] (* _Paolo Xausa_, Apr 27 2024 *)
%o A093753 (PARI) Pi*log(2)/2 - Catalan \\ _Michel Marcus_, Sep 22 2014
%Y A093753 Cf. A001008, A002805, A006752, A093754, A173623.
%K A093753 nonn,cons
%O A093753 0,2
%A A093753 _Eric W. Weisstein_, Apr 15 2004