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%I #10 Sep 08 2022 08:45:27
%S 2,3,0,4,7,6,4,8,7,0,9,6,2,4,8,6,5,0,5,2,4,1,1,5,0,2,2,3,5,4,6,8,5,5,
%T 1,1,3,4,4,4,5,0,1,8,8,7,6,0,6,3,2,1,1,6,2,0,6,3,1,0,6,2,9,6,4,6,6,8,
%U 5,3,3,4,2,7,7,8,4,7,9,5,9,6,3,7,9,1,1,1,4,2,1,9,7,4,7,6,1,7,9,3,6,1,5,1,5
%N Decimal expansion of cosecant of 180/7 = 25.7142857+ degrees = csc(Pi/7).
%C 1 + csc(Pi/7) is the radius of the smallest circle into which 8 unit circles can be packed ("r=3.304+ Proved by Braaksma in 1963.", according to the Friedman link, which has a diagram).
%C csc(Pi/7) is the distance between the center of the larger circle and the center of each unit circle that touches the larger circle.
%H G. C. Greubel, <a href="/A121598/b121598.txt">Table of n, a(n) for n = 1..10000</a>
%H E. Friedman, <a href="https://erich-friedman.github.io/packing/cirincir/">Erich's Packing Center: "Circles in Circles"</a>
%e 2.304764870962486505241150223546855...
%t RealDigits[Csc[Pi/7], 10, 100][[1]] (* _G. C. Greubel_, Nov 02 2018 *)
%o (PARI) 1/sin(Pi/7)
%o (Magma) SetDefaultRealField(RealField(100)); R:= RealField(); 1/Sin(Pi(R)/7); // _G. C. Greubel_, Nov 02 2018
%Y Cf. A121570.
%K cons,nonn
%O 1,1
%A _Rick L. Shepherd_, Aug 09 2006
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