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 A246859 #11 Jan 17 2020 16:12:27
%S A246859 3,4,6,1,1,8,9,6,5,6,0,5,9,3,3,4,5,0,9,9,6,0,9,0,5,4,2,0,6,8,7,6,5,9,
%T A246859 1,5,9,8,3,9,5,2,8,1,3,8,5,9,7,4,8,6,4,0,1,6,3,8,0,5,8,7,7,3,1,1,3,5,
%U A246859 8,2,9,0,2,6,8,1,8,2,6,3,6,4,6,1,5,2,8,7,9,5,5,1,0,8,9,7,3,4,2,3,8,6,8,4
%N A246859 Decimal expansion of the best constant K for the integral inequality integral_{0..1} f(x)^2*f'(x)^2 dx <= K*integral_{0..1} f'(x)^4 dx.
%D A246859 Steven R. Finch, Mathematical Constants, Cambridge University Press, 2003, Section 3.6 Sobolev Isoperimetric Constants.
%H A246859 David W. Boyd, <a href="http://projecteuclid.org/euclid.pjm/1102978495">Best constants in a class of integral inequalities</a>, Pacific J. Math. Volume 30, Number 2 (1969), 367-383
%H A246859 Steven R. Finch, <a href="http://arxiv.org/abs/2001.00578">Errata and Addenda to Mathematical Constants</a>, p. 30.
%F A246859 24/(2*sqrt(3) + 3*sqrt(2)*arcsinh(sqrt(2)))^2.
%e A246859 0.34611896560593345099609054206876591598395281385974864...
%t A246859 (* Using Boyd's formula *) I0[p_, q_, r_] := Integrate[(((q - 1)*t + 1)*t^(1/p - 1))/ (((r*(q - 1))*t)/(r - q) + 1)^((r*p + p + q)/(r*p)), {t, 0, 1}]; K[p_, q_, r_] := (beta = (((r - 1)*p + (r - q))/((r - 1)*(p + q)))^(1/r); (((r - q)*p^p)*beta^(p + q - r))/(I0[p, q, r]^p*((r - 1)*(p + q)))); RealDigits[K[2, 2, 4], 10, 104] // First
%Y A246859 Cf. A242440, A244263, A244347, A244354, A245292.
%K A246859 nonn,cons
%O A246859 1,1
%A A246859 _Jean-François Alcover_, Sep 05 2014