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 A200257 #20 Oct 30 2018 10:31:02
%S A200257 5,5,0,6,2,9,9,6,3,8,6,6,8,1,3,1,8,1,9,8,8,4,3,9,5,0,6,3,3,1,3,1,8,8,
%T A200257 1,6,6,3,2,5,3,5,3,9,0,5,5,1,8,2,7,9,2,0,0,0,3,9,6,8,0,3,8,8,6,5,0,1,
%U A200257 1,9,7,7,6,2,9,3,6,2,9,1,1,1,8,8,9
%N A200257 Decimal expansion of the circumradius R of cyclic pentagon with sides 2, 3, 5, 7, and 11.
%C A200257 Note that for cyclic polygon R does not depend on order of sides.
%H A200257 Ralph H. Buchholz and James A. MacDougall, <a href="http://dx.doi.org/10.1016/j.jnt.2007.05.005">Cyclic polygons with rational Sides and Area</a>, Journal of Number Theory, Volume 128, Issue 1, January 2008, Pages 17-48.
%H A200257 Zak Seidov, <a href="/A200257/a200257.png">Figure showing polygon</a>
%e A200257 R = 5.5062996386681...
%t A200257 nn=5; L=Sum[Prime[n],{n,nn}]; RealDigits[Re[FindRoot[Sum[ArcSin[Prime[n]/2/R], {n,nn}] == Pi, {R,L/2/Pi}][[1,2]]]]
%K A200257 nonn,cons
%O A200257 1,1
%A A200257 _Zak Seidov_, Nov 15 2011