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 A232247 #14 Mar 24 2021 22:39:13
%S A232247 5,6,6,9,1,1,5,0,4,9,4,1,0,0,9,4,0,5,0,8,2,8,9,7,7,4,6,7,2,2,6,1,9,1,
%T A232247 5,3,8,0,6,4,8,0,2,3,9,0,9,2,6,8,2,3,3,5,7,5,7,7,5,9,4,7,2,0,4,5,8,9,
%U A232247 3,0,1,1,7,5,9,7,0,9,1,8,2,7,5,3,1,0
%N A232247 Decimal expansion of the arctan of 2/Pi.
%F A232247 Equals A019669 - A232182.
%F A232247 Equals Sum_{k>=0} (-1)^k*(2/Pi)^(1+2*k)/(1+2*k).
%e A232247 0.56691150494100940508289774672261915380648023909268233575775947204589...
%p A232247 evalf(arctan(2/Pi));
%t A232247 RealDigits[ArcTan[2/Pi], 10, 90][[1]]
%o A232247 (PARI) atan(2/Pi) \\ _Charles R Greathouse IV_, Mar 24 2021
%Y A232247 Cf. A060294, A232182.
%K A232247 nonn,cons
%O A232247 0,1
%A A232247 _Bruno Berselli_, Nov 21 2013