%I
%S 5,7,8,4,1,6,7,6,2,7,8,8,9,0,0,7,5,9,0,7,4,6,0,2,0,5,8,1,4,6,1,9,5,6,
%T 7,4,7,9,9,4,8,3,9,6,9,4,3,6,6,4,5,5,0,1,5,4,8,3,1,7,6,7,4,9,4,1,7,9,
%U 6,0,2,0,8,2,4,1,2,2,0,7,1,4,5,0,6,5,8,2,7,4,8,7,0,0,2,7,9,3,9,1
%N Decimal expansion of k3, a Diophantine approximation constant such that the conjectured volume of the "critical parallelepiped" is 2^3*k3 (the 3D analog of A242671).
%D Steven R. Finch, Mathematical Constants, Cambridge University Press, 2003, Section 2.23 Diophantine approximation constants, p. 176.
%F 8/7*cos(2*Pi/7)*cos(Pi/7)^2.
%F Also equals the positive root of 343*x^3  147*x^2  28*x  1.
%e 0.578416762788900759074602058146195674799483969436645501548317674941796...
%t RealDigits[8/7*Cos[2*Pi/7]*Cos[Pi/7]^2, 10, 100] // First
%Y Cf. A242671.
%K nonn,cons,easy
%O 0,1
%A _JeanFrançois Alcover_, Jul 16 2014
