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 A377981 #4 Nov 13 2024 16:39:19
%S A377981 1,8,5,7,8,4,5,3,5,8,0,0,6,5,9,2,4,1,2,1,4,7,1,5,6,4,5,1,8,6,4,9,0,3,
%T A377981 1,1,9,6,9,7,5,1,7,2,4,5,9,4,6,7,5,2,8,0,3,4,2,5,2,4,6,5,3,1,6,1,5,9,
%U A377981 2,9,4,1,2,4,1,0,3,4,6,3,6,4,3,5,8,8,7,1,3,6,2,6,1,7,2,4,6,7,4,9
%N A377981 Decimal expansion of G/2 - Pi*log(2)/8, where G = A006752.
%D A377981 Steven R. Finch, Mathematical Constants, Encyclopedia of Mathematics and its Applications, vol. 94, Cambridge University Press, 2003, Section 1.7.2, p. 55.
%H A377981 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. 230.
%F A377981 Equals Sum_{n>=0} (-1)^(n+1)/(2*n + 1) Sum_{k=0..n-1} 1/(2*k + 1) (see Finch).
%F A377981 Equals Integral_{x=0..Pi/4} x*tan(x) dx (see Shamos).
%F A377981 Equals A006752/2 - A102886.
%e A377981 0.18578453580065924121471564518649031196975172459...
%t A377981 RealDigits[Catalan/2-Pi Log[2]/8,10,100][[1]]
%Y A377981 Cf. A006752, A102886.
%K A377981 nonn,cons
%O A377981 0,2
%A A377981 _Stefano Spezia_, Nov 13 2024