OFFSET
1,1
COMMENTS
1 + csc(Pi/7) is the radius of the smallest circle into which 8 unit circles can be packed ("r=3.304+ Proved by Braaksma in 1963.", according to the Friedman link, which has a diagram).
csc(Pi/7) is the distance between the center of the larger circle and the center of each unit circle that touches the larger circle.
LINKS
G. C. Greubel, Table of n, a(n) for n = 1..10000
E. Friedman, Erich's Packing Center: "Circles in Circles"
EXAMPLE
2.304764870962486505241150223546855...
MATHEMATICA
RealDigits[Csc[Pi/7], 10, 100][[1]] (* G. C. Greubel, Nov 02 2018 *)
PROG
(PARI) 1/sin(Pi/7)
(Magma) SetDefaultRealField(RealField(100)); R:= RealField(); 1/Sin(Pi(R)/7); // G. C. Greubel, Nov 02 2018
CROSSREFS
KEYWORD
cons,nonn
AUTHOR
Rick L. Shepherd, Aug 09 2006
STATUS
approved