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%I A232817 #13 May 17 2023 08:41:26
%S A232817 3,6,9,0,5,4,0,2,9,7,2,8,8,0,5,6,8,3,8,1,9,3,6,0,7,7,5,9,1,7,7,9,7,6,
%T A232817 0,5,3,5,6,0,0,7,2,5,3,2,4,3,1,9,0,3,3,2,5,4,5,1,0,1,7,9,4,6,6,6,9,5,
%U A232817 3,5,8,8,7,6,7,5,1,9,9,3,0,1,3,1,0,6,1,8,9,5,7,2,7,7,3,8,7,5,6,9,3,6,1,1,1
%N A232817 Decimal expansion of the open-tube surface index constant.
%C A232817 The external surface index of an open-ended cylinder (tube) equals this constant, multiplied by (Length/Diameter)^(1/3).
%C A232817 For a general definition of surface index, see A232808.
%H A232817 Stanislav Sykora, <a href="/A232817/b232817.txt">Table of n, a(n) for n = 1..1000</a>
%H A232817 Wikipedia, <a href="http://en.wikipedia.org/wiki/Cylinder_%28geometry%29">Cylinder (geometry)</a>.
%F A232817 Equals (16*Pi)^(1/3) = 2*(2*Pi)^(1/3).
%t A232817 RealDigits[2 * Surd[2 * Pi, 3], 10, 120][[1]] (* _Amiram Eldar_, May 17 2023 *)
%Y A232817 Cf. Other surface indices: A232808 (spheres), A232809, A232810, A232811, A232812 (platonic solids), A232813 (closed cylinders), A232814 (open cylinders), A232815 (closed cones), A232816 (open cones).
%K A232817 nonn,cons,easy
%O A232817 1,1
%A A232817 _Stanislav Sykora_, Dec 05 2013

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