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 A263031 #11 Jan 07 2021 07:30:01
%S A263031 0,1,4,5,3,7,4,2,9,1,8,3,2,8,4,0,3,3,6,0,5,0,2,0,2,9,4,5,0,2,2,6,2,0,
%T A263031 9,0,3,6,0,5,4,1,4,9,7,5,9,3,4,6,4,4,4,1,3,8,1,5,2,2,4,7,4,0,5,5,3,4,
%U A263031 6,9,2,7,4,4,9,5,5,0,0,8,3,1,2,5,9,0,7,2,3,8,9,0,1,2,7,7,0,9,8,8,3,6,0,5,4,4
%N A263031 Decimal expansion of a constant related to A262877 and A262947 (negated).
%F A263031 Integral_{x=0..infinity} 1/x*(exp(-x)/(1 - exp(-3*x))^2 - 1/(9*x^2) - 2/(9*x) - 5*exp(-x)/36) dx.
%F A263031 exp(3*(A263030+A263031)) = A^2 * Gamma(1/3) / (3^(11/12) * exp(1/6) * sqrt(2*Pi)), where A = A074962 is the Glaisher-Kinkelin constant.
%e A263031 -0.01453742918328403360502029450226209036054149759346444138152247405534...
%t A263031 NIntegrate[1/x*(Exp[-x]/(1 - Exp[-3*x])^2 - 1/(9*x^2) - 2/(9*x) - 5*Exp[-x]/36), {x, 0, Infinity}, WorkingPrecision -> 120, MaxRecursion -> 100, PrecisionGoal -> 110]
%Y A263031 Cf. A262876, A262877, A262946, A262947, A263030, A075700, A084448, A263405, A263414.
%K A263031 nonn,cons
%O A263031 0,3
%A A263031 _Vaclav Kotesovec_, Oct 08 2015