This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A120670 #9 Feb 17 2023 15:25:56 %S A120670 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 A120670 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 A120670 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 A120670 Decimal expansion of 180*arccos(1-8/(Pi^2))/Pi. %C A120670 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 A120670 Equals 180*A120669/Pi = 360*A120671. %e A120670 79.0804474956203908253980311180... %t A120670 RealDigits[180 ArcCos[1-8/Pi^2]/Pi,10,120][[1]] (* _Harvey P. Dale_, Feb 17 2023 *) %o A120670 (PARI) 180*acos(1-8/Pi^2)/Pi %Y A120670 Cf. A088538, A120669 (same in radians), A120671 (A120670/360). %K A120670 cons,nonn %O A120670 2,1 %A A120670 _Rick L. Shepherd_, Jun 22 2006