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%I #5 Jun 23 2022 13:49:16
%S 1,7,0,3,0,8,2,4,9,6,6,5,8,9,5,3,2,2,7,8,3,5,8,4,9,1,2,2,7,4,9,2,0,3,
%T 1,5,7,1,9,8,0,3,4,4,2,2,9,5,0,4,9,7,7,1,2,1,2,1,6,6,0,3,7,8,4,2,1,7,
%U 2,6,9,2,4,5,5,2,3,3,5,0,4,9,0,3,5,1,6,3,3,3,3,1,2,3,5,3,4,0,2,3,8,9,5,7,0
%N Decimal expansion of the perimeter of the region that represents the set of points in a unit square that are closer to the center of the square than to the closest edge.
%C The shape is formed by the intersection of four parabolas. Its area is given in A355183.
%H Amiram Eldar, <a href="/A355183/a355183.jpg">Illustration</a>.
%H Missouri State University, <a href="http://people.missouristate.edu/lesreid/Adv05.html">Problem #5, The Area and Perimeter of a Certain Region</a>, Advanced Problem Archive; <a href="http://people.missouristate.edu/lesreid/AdvSol05.html">Solution to Problem #5</a>, by John Shonder.
%F Equals 2*log(sqrt(4-2*sqrt(2))+sqrt(2)-1) - sqrt(16-8*sqrt(2)) + sqrt(32-16*sqrt(2)).
%e 1.70308249665895322783584912274920315719803442295049...
%t RealDigits[2*Log[Sqrt[4 - 2*Sqrt[2]] + Sqrt[2] - 1] - Sqrt[16 - 8*Sqrt[2]] + Sqrt[32 - 16*Sqrt[2]], 10, 100][[1]]
%Y Cf. A103712, A244921, A254140, A352453, A355183 (area).
%K nonn,cons
%O 1,2
%A _Amiram Eldar_, Jun 23 2022