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 A272335 #21 Nov 18 2024 03:33:18
%S A272335 1,1,4,2,7,2,8,1,2,6,9,3,0,6,8,1,2,8,4,8,1,0,2,1,8,4,5,9,5,6,6,5,7,1,
%T A272335 1,1,9,3,0,1,1,0,1,5,0,4,5,2,9,4,7,0,2,3,9,5,7,1,7,1,2,5,3,0,9,9,2,9,
%U A272335 0,5,7,4,5,0,5,6,8,1,5,3,5,5,5,8,4,0,1,0,3,0,3,3,7,4,0,2,6,8,2,9,9
%N A272335 Decimal expansion of a function approximation constant which is the analog of Gibbs's constant 2*G/Pi (A036793) for de la Vallée-Poussin sums.
%D A272335 Steven R. Finch, Mathematical Constants, Cambridge University Press, 2003, Section 4.1 Gibbs-Wilbraham Constant, p. 248.
%H A272335 R. P. Boyer and W. M. Y. Goh <a href="http://www.math.drexel.edu/~rboyer/papers/generalized_gibbs.pdf">Generalized Gibbs phenomenon for Fourier partial sums and de la Vallée-Poussin sums</a>, J. Appl. Math. Comput. 37 (2011) 421-442, p. 11.
%H A272335 Steven R. Finch, <a href="http://arxiv.org/abs/2001.00578">Errata and Addenda to Mathematical Constants</a>, arXiv:2001.00578 [math.HO], 2020-2024; p. 33.
%F A272335 Equals (2/Pi)*Integral_{t=0..2*Pi/3} (cos(t) - cos(2*t))/t^2 dt.
%F A272335 Equals (2/Pi)*(2*Si(4*Pi/3) - Si(2*Pi/3)), where Si is the Sine integral function.
%e A272335 1.14272812693068128481021845956657111930110150452947023957171253...
%t A272335 (2/Pi)(2 SinIntegral[4 Pi/3] - SinIntegral[2 Pi/3]) // N[#, 101]& // RealDigits // First
%Y A272335 Cf. A036792, A036793, A243267, A243268, A245535.
%K A272335 nonn,cons
%O A272335 1,3
%A A272335 _Jean-François Alcover_, Apr 26 2016