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 A233527 #32 Nov 09 2018 07:30:04 %S A233527 1,5,7,8,3,1,1,9,0,2,8,8,1,5,8,8,6,0,1,6,7,6,0,8,7,4,1,7,8,2,8,1,8,9, %T A233527 2,3,6,0,5,0,7,1,2,4,0,5,9,9,0,5,1,0,6,0,4,1,5,5,5,7,9,6,7,2,1,3,8,2, %U A233527 2,1,1,9,5,6,5,1,8,2,1,0,9,1,6,0,5,8,7,1,3,9,4,4,0,8,0,3,1,4,0,0 %N A233527 Decimal expansion of arctan( 1/(2*Pi) ): opposite angle for a right triangle of equal area to a circle. %H A233527 Wikipedia, <a href="https://en.wikipedia.org/wiki/Area_of_a_circle#Triangle_proof">Area of a circle: Triangle proof</a> %F A233527 Equals arctan(1/A019692). %F A233527 Equals A019669 - A233528. [_Bruno Berselli_, Dec 16 2013] %e A233527 0.15783119028815886016760874178281892360507124059905106041555796721382... %t A233527 RealDigits[ArcTan[1/(2 Pi)], 10, 110][[1]] (* _Bruno Berselli_, Dec 16 2013 *) %o A233527 (PARI) atan(1/(2*Pi)) %Y A233527 Cf. A019669, A019692, A086201, A233528. %K A233527 nonn,cons %O A233527 0,2 %A A233527 _John W. Nicholson_, Dec 11 2013 %E A233527 More terms from _Ralf Stephan_, Dec 16 2013