A120670 - OEIS

%I #9 Feb 17 2023 15:25:56

%S 7,9,0,8,0,4,4,7,4,9,5,6,2,0,3,9,0,8,2,5,3,9,8,0,3,1,1,1,8,0,5,2,2,5,

%T 9,2,5,9,3,8,2,1,1,8,6,5,0,5,9,5,4,7,1,1,3,2,0,5,6,4,7,9,0,0,2,6,4,0,

%U 4,1,4,5,4,1,6,7,2,6,1,7,0,6,2,7,9,4,2,3,9,0,6,9,0,7,1,5,5,1,7,5,7,3,7,1,1

%N Decimal expansion of 180*arccos(1-8/(Pi^2))/Pi.

%C For a circle with radius r, the measurement in degrees of the central angle with endpoints on the circle that are r*4/Pi apart: The average central angle (<= 180 degrees) 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.

%F Equals 180*A120669/Pi = 360*A120671.

%e 79.0804474956203908253980311180...

%t RealDigits[180 ArcCos[1-8/Pi^2]/Pi,10,120][[1]] (* _Harvey P. Dale_, Feb 17 2023 *)

%o (PARI) 180*acos(1-8/Pi^2)/Pi

%Y Cf. A088538, A120669 (same in radians), A120671 (A120670/360).

%K cons,nonn

%O 2,1

%A _Rick L. Shepherd_, Jun 22 2006