A133749 - OEIS

%I #19 Feb 16 2025 08:33:06

%S 6,9,4,5,9,2,7,1,0,6,6,7,7,2,1,3,9,5,4,0,6,8,6,6,5,0,7,0,7,7,2,5,9,1,

%T 8,4,0,0,1,5,0,2,7,0,8,7,3,6,2,7,7,5,4,8,9,4,4,9,6,5,5,1,2,5,2,8,2,6,

%U 3,2,8,8,5,5,6,0,5,8,9,4,1,6,8,6,0,6,6,4,5,2,6,2,9,5,9,8,2,9,6,0,4,7,8,3,6

%N Decimal expansion of -2*cos((2*Pi)/9) + 2*sqrt(3)*sin((2*Pi)/9).

%C The distance between the centers of 2 unit-radius spheres such that the volume of the overlap is equal to half the volume of each sphere. - _Amiram Eldar_, May 31 2021

%H Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/Sphere-SphereIntersection.html">Sphere-Sphere Intersection</a>.

%F Equals 4*sin(Pi/18) = 4*A019819. - _Gleb Koloskov_, Feb 28 2021

%e 0.69459271066772139540...

%t RealDigits[-2*Cos[(2*Pi)/9] + 2*Sqrt[3]*Sin[(2*Pi)/9], 10, 100][[1]] (* _Vaclav Kotesovec_, Aug 16 2015 *)

%o (PARI) 4*sin(Pi/18) \\ _Gleb Koloskov_, Feb 28 2021

%Y Cf. A019819.

%K nonn,cons,changed

%O 0,1

%A _Eric W. Weisstein_, Sep 23 2007