A120669 Decimal expansion of arccos(1-8/(Pi^2)).

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

Offset: 1

Author

Rick L. Shepherd, Jun 22 2006

Keywords

• cons
• nonn

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.

Examples

			1.38021418274907990400875581814...
		

Crossrefs

Cf. A088538, A120670 (same in degrees), A120671 (A120669/2Pi).

Programs

Mathematica

RealDigits[ArcCos[1-8/Pi^2],10,120][[1]] (* Harvey P. Dale, Dec 15 2014 *)

PARI

acos(1-8/Pi^2)