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 A243445 #19 Nov 12 2018 03:02:46 %S A243445 1,2,0,5,9,3,2,4,9,8,6,8,1,4,1,3,4,3,7,5,0,3,9,2,3,3,6,1,7,3,3,0,9,1, %T A243445 0,9,4,4,0,0,3,3,1,7,4,2,6,6,3,6,9,6,0,6,5,1,3,2,9,9,7,5,5,0,4,2,2,9, %U A243445 9,8,7,5,3,3,0,9,7,2,0,9,2,9,9,1,6,2,7 %N A243445 Decimal expansion of the polar angle of the cone circumscribed to a regular dodecahedron from one of its vertices. %C A243445 The angle is in radians. %H A243445 Stanislav Sykora, <a href="/A243445/b243445.txt">Table of n, a(n) for n = 1..2000</a> %H A243445 Wikipedia, <a href="http://en.wikipedia.org/wiki/Dodecahedron">Dodecahedron</a> (use the point coordinates to derive the formula). %F A243445 arccos(1/(phi*sqrt(3))), where phi = A001622. %F A243445 arctan(phi^2), where phi = A001622. - _Jon Maiga_, Nov 11 2018 %e A243445 1.20593249868141343750392336173309109440033174266369606513299755... %t A243445 RealDigits[ArcCos[1/(GoldenRatio Sqrt[3])],10,120][[1]] (* _Harvey P. Dale_, May 17 2016 *) %o A243445 (PARI) acos(2/(1+sqrt(5))/sqrt(3)) %Y A243445 Cf. A001622 (phi), A003881 (octahedron), A195695 (tetrahedron), A195696 (cube), A195723 (isosahedron). %K A243445 nonn,cons %O A243445 1,2 %A A243445 _Stanislav Sykora_, Jun 06 2014