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 A256922 #21 Apr 27 2025 09:09:42
%S A256922 1,6,7,8,2,5,5,9,4,8,1,5,5,2,1,2,0,7,9,5,7,7,3,7,5,9,9,2,5,9,5,5,4,0,
%T A256922 0,3,2,6,9,2,2,6,9,4,0,0,6,7,3,6,2,3,3,1,0,3,9,0,1,5,1,4,3,6,8,5,1,0,
%U A256922 9,1,2,6,3,6,1,5,5,0,6,5,9,7,5,4,4,2,1,8,3,9,7,8,7,1,9,9,5,4,1,0,6,6,3,1,9
%N A256922 Decimal expansion of Sum_{k>=2} (-1)^k*zeta(k)/(k*2^k).
%D A256922 H. M. Srivastava and Junesang Choi, Zeta and q-Zeta Functions and Associated Series and Integrals, Elsevier Insights (2011) p. 272.
%H A256922 G. C. Greubel, <a href="/A256922/b256922.txt">Table of n, a(n) for n = 0..10000</a>
%H A256922 Eric Weisstein's MathWorld, <a href="https://mathworld.wolfram.com/RiemannZetaFunction.html">Riemann Zeta Function</a>
%H A256922 Wikipedia, <a href="http://en.wikipedia.org/wiki/Riemann_zeta_function">Riemann Zeta Function</a>
%F A256922 Equals A001620/2 + (1/2)*log(Pi) - log(2).
%F A256922 Equals Sum_{k>=1} (1/(2*k) - log(1 + 1/(2*k))). - _Amiram Eldar_, Jul 22 2020
%F A256922 Equals (A001620 - A094640)/2. - _Ruud H.G. van Tol_, Apr 26 2025
%e A256922 0.167825594815521207957737599259554003269226940067362331039...
%t A256922 RealDigits[EulerGamma/2 + (1/2)*Log[Pi] - Log[2], 10, 105] // First
%o A256922 (PARI) Euler/2 + log(Pi)/2 - log(2) \\ _Michel Marcus_, Apr 13 2015
%o A256922 (Magma) SetDefaultRealField(RealField(100)); R:= RealField(); EulerGamma(R)/2 + (1/2)*Log(Pi(R)) - Log(2); // _G. C. Greubel_, Sep 05 2018
%Y A256922 Cf. A001620, A002162, A053510, A094640, A256921.
%K A256922 nonn,cons,easy
%O A256922 0,2
%A A256922 _Jean-François Alcover_, Apr 13 2015