This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A165922 #13 Feb 16 2025 08:33:11 %S A165922 1,2,2,5,1,7,5,3,2,3,1,5,9,5,3,7,8,8,7,8,0,2,9,4,7,7,7,4,0,2,8,8,2,0, %T A165922 9,8,0,8,8,3,0,8,1,0,6,7,4,8,1,4,2,3,6,7,2,8,8,7,4,8,0,0,4,5,0,9,1,1, %U A165922 7,8,4,5,2,1,5,3,9,3,2,8,7,7,4,2,3,0,6,6,7,3,0,7,1,8,1,5,7,5,3,1,5,7,2,6,6 %N A165922 Decimal expansion of 2*sqrt(3)/(9*Pi). %C A165922 The ratio of the volume of a regular tetrahedron to the volume of the circumscribed sphere. (The MathWorld link shows that the circumradius for a tetrahedron with side length a is a*sqrt(6)/4.) %H A165922 Frank Jackson and Eric W. Weisstein, <a href="https://mathworld.wolfram.com/Tetrahedron.html">Tetrahedron</a> %H A165922 <a href="/index/Tra#transcendental">Index entries for transcendental numbers</a> %F A165922 2*sqrt(3)/(9*Pi) = A010469/(9*A000796) = (2/9)*A002194/A000796 = (2/9)*A002194*A049541 = 2*A020784/A000796 = 2*3^(-3/2)/Pi. %e A165922 0.122517532315953788780294777402882098... %t A165922 RealDigits[(2Sqrt[3])/(9Pi),10,120][[1]] (* _Harvey P. Dale_, Nov 17 2013 *) %o A165922 (PARI) 2*3^(-3/2)/Pi %Y A165922 Cf. A000796, A002194, A010469, A049541, A020784. %K A165922 cons,nonn %O A165922 0,2 %A A165922 _Rick L. Shepherd_, Sep 30 2009