OFFSET
1,2
COMMENTS
The radius of a common circle surrounded by n tangent unit circles (n > 2) is r = 1/sin(Pi/n) - 1.
LINKS
Andrew M. Gleason, Angle Trisection, the Heptagon, and the Triskaidecagon, The American Mathematical Monthly 95, no. 3 (March 1988), pp. 185-194.
FORMULA
Equals 1 / sin(Pi/7) - 1.
Equals A121598 - 1.
EXAMPLE
1.3047648709624865052...
MATHEMATICA
RealDigits[Csc[Pi/7] - 1, 10, 120][[1]] (* Amiram Eldar, Dec 28 2023 *)
PROG
(PARI) 1/sin(Pi/7) - 1
CROSSREFS
KEYWORD
AUTHOR
Thomas Otten, Dec 23 2023
EXTENSIONS
More digits from Jon E. Schoenfield, Dec 24 2023
Comments edited by Michal Paulovic, Dec 26 2023
STATUS
approved