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 A236367 #15 May 17 2023 08:41:22 %S A236367 2,4,1,1,8,6,4,9,9,7,3,6,2,8,2,6,8,7,5,0,0,7,8,4,6,7,2,3,4,6,6,1,8,2, %T A236367 1,8,8,8,0,0,6,6,3,4,8,5,3,2,7,3,9,2,1,3,0,2,6,5,9,9,5,1,0,0,8,4,5,9, %U A236367 9,7,5,0,6,6,1,9,4,4,1,8,5,9,8,3,2,5,5,1,4,1,7,5,2,2,6,4,3,5,6,7,7,7,4,0,5 %N A236367 Dihedral angle in a regular icosahedron (radians). %H A236367 Stanislav Sykora, <a href="/A236367/b236367.txt">Table of n, a(n) for n = 1..2000</a> %H A236367 Wikipedia, <a href="http://en.wikipedia.org/wiki/Platonic_solid">Platonic solid</a>. %F A236367 Equals 2*arctan(phi^2) = 2*arctan(A001622^2) = 2*arctan((3+sqrt(5))/2). %e A236367 2.41186499736282687500784672346618218880066348532739213... %t A236367 RealDigits[2 * ArcTan[GoldenRatio^2], 10, 120][[1]] (* _Amiram Eldar_, May 17 2023 *) %o A236367 (PARI) 2*atan((3+sqrt(5))/2) %Y A236367 Cf. A001622, Platonic solids dihedral angles: A137914 (tetrahedron), A156546 (octahedron), A019669 (cube), A137218 (dodecahedron). %K A236367 nonn,cons,easy %O A236367 1,1 %A A236367 _Stanislav Sykora_, Jan 23 2014