OFFSET
0,1
REFERENCES
Steven R. Finch, Mathematical Constants, Cambridge University Press, 2003, Section 2.23 Diophantine approximation constants, p. 176.
FORMULA
8/7*cos(2*Pi/7)*cos(Pi/7)^2.
Also equals the positive root of 343*x^3 - 147*x^2 - 28*x - 1.
EXAMPLE
0.578416762788900759074602058146195674799483969436645501548317674941796...
MATHEMATICA
RealDigits[8/7*Cos[2*Pi/7]*Cos[Pi/7]^2, 10, 100] // First
CROSSREFS
KEYWORD
AUTHOR
Jean-François Alcover, Jul 16 2014
STATUS
approved