OFFSET
1,2
COMMENTS
For a circle with radius r, the measurement in radians of the central angle with endpoints on the circle that are r*4/Pi apart: The average central angle (<= Pi) formed using two randomly chosen points on a circle. The average arc length between such endpoints is r*A120669 corresponding to the average chord length r*A088538; so for the unit circle arc length is A120669 and chord length is A088538.
EXAMPLE
1.38021418274907990400875581814...
MATHEMATICA
RealDigits[ArcCos[1-8/Pi^2], 10, 120][[1]] (* Harvey P. Dale, Dec 15 2014 *)
PROG
(PARI) acos(1-8/Pi^2)
CROSSREFS
KEYWORD
cons,nonn
AUTHOR
Rick L. Shepherd, Jun 22 2006
STATUS
approved