Year-end appeal: Please make a donation to the OEIS Foundation to support ongoing development and maintenance of the OEIS. We are now in our 61st year, we have over 378,000 sequences, and we’ve reached 11,000 citations (which often say “discovered thanks to the OEIS”).
%I #16 Nov 21 2024 08:04:53
%S 4,1,4,2,9,3,3,0,2,5,9,5,0,3,3,7,7,7,4,3,0,8,4,1,0,7,8,5,7,5,3,0,3,2,
%T 5,1,8,5,6,4,2,3,9,8,1,3,0,8,2,4,8,9,4,8,0,5,0,5,7,7,6,9,7,9,5,8,9,5,
%U 9,2,8,8,6,6,1,0,1,8,6,9,5,5,8,9,0,5,7,1,9,5,0,4,7,4,2,8,1,2,3,9,5,0
%N Decimal expansion of (2 + 4*sqrt(2) + (4 + sqrt(2))*arcsinh(1))/30.
%C Average length of a line picked at random inside an isosceles right triangle with legs of unit length.
%C Close but not equal to sqrt(2)-1 = 0.414213562.
%H G. C. Greubel, <a href="/A093063/b093063.txt">Table of n, a(n) for n = 0..10000</a>
%H Eric Weisstein's World of Mathematics, <a href="http://mathworld.wolfram.com/TriangleLinePicking.html">Triangle Line Picking</a>
%H <a href="/index/Tra#transcendental">Index entries for transcendental numbers</a>
%e 0.41429330259503377743084107857530325185642398130824894805...
%t RealDigits[(2+4Sqrt[2]+(4+Sqrt[2])ArcSinh[1])/30,10,120][[1]] (* _Harvey P. Dale_, Jan 20 2012 *)
%o (PARI) default(realprecision, 100); (2+4*sqrt(2)+(4+sqrt(2))*asinh(1))/30 \\ _G. C. Greubel_, Sep 27 2018
%o (Magma) SetDefaultRealField(RealField(100)); (2+4*Sqrt(2)+(4+Sqrt(2) )*Argsinh(1))/30; // _G. C. Greubel_, Sep 27 2018
%Y Cf. A093064.
%K nonn,cons
%O 0,1
%A _Eric W. Weisstein_, Mar 16 2004