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%I #27 Apr 22 2022 05:42:12
%S 3,7,7,1,2,3,6,1,6,6,3,2,8,2,5,3,4,6,3,4,7,1,1,6,9,9,3,1,2,2,5,8,6,1,
%T 5,4,2,8,5,2,4,5,8,3,3,4,3,3,8,5,2,8,1,9,5,1,3,7,8,1,2,6,3,4,6,4,1,9,
%U 5,3,2,7,5,8,9,8,9,5,2,1,0,3,6,0,1,0,3,3,4,2,4,8,7,3,7,1,0,8
%N Decimal expansion of 8*sqrt(2) / 3.
%C 8*sqrt(2) / (3*a) is the maximum curvature of the Folium of Descartes x^3 + y^3 - 3*a*x*y = 0, occurring at the point M of coordinates (3a/2, 3a/2). The corresponding minimum radius of curvature is (3*sqrt(2))*a/16.
%C This point M is at the intersection of the first bisector with the loop, distinct from O (see curves).
%H Robert Ferréol, <a href="https://mathcurve.com/courbes2d.gb/foliumdedescartes/foliumdedescartes.shtml">Cartesian folium</a>, Mathcurve.
%H John A. Tierney, <a href="https://cms.math.ca/wp-content/uploads/crux-pdfs/Crux_v5n10_Dec.pdf">Problem 417</a>, Crux Mathematicorum, Vol. 5, No. 10 (1979), pp. 308-310.
%H Eric Weisstein's World of Mathematics, <a href="http://mathworld.wolfram.com/FoliumofDescartes.html">Folium of Descartes</a>.
%H Wikipedia, <a href="https://en.wikipedia.org/wiki/Folium_of_Descartes">Folium of Descartes</a>.
%H <a href="https://oeis.org/wiki/Index_to_OEIS:_Section_Cu">Index to sequences related to curves</a>.
%F Equals 8*A131594.
%e 3.771236166328253463471169931225...
%p evalf(8*sqrt(2)/3,100);
%t RealDigits[8*Sqrt[2]/3, 10, 100][[1]] (* _Amiram Eldar_, Apr 20 2022 *)
%o (PARI) 8*sqrt(2)/3 \\ _Michel Marcus_, Apr 20 2022
%Y Cf. A295709 (arc length of the loop of the Folium of Descartes).
%Y Cf. A002193, A131594.
%K nonn,cons
%O 1,1
%A _Bernard Schott_, Apr 20 2022