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 A378977 #11 Mar 31 2025 03:28:55 %S A378977 2,8,0,3,2,1,7,8,5,6,0,8,4,8,0,5,9,6,2,1,0,3,4,4,9,3,2,6,4,8,7,7,2,5, %T A378977 3,2,8,1,1,5,2,6,5,9,8,8,0,3,5,4,0,1,2,6,9,8,4,7,0,1,7,0,6,0,5,1,6,8, %U A378977 7,6,1,6,4,9,4,7,8,1,9,2,7,5,1,4,3,8,7,6,5,3 %N A378977 Decimal expansion of the dihedral angle, in radians, between any two adjacent faces in a triakis icosahedron. %C A378977 The triakis icosahedron is the dual polyhedron of the truncated dodecahedron. %H A378977 Paolo Xausa, <a href="/A378977/b378977.txt">Table of n, a(n) for n = 1..10000</a> %H A378977 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/TriakisIcosahedron.html">Triakis Icosahedron</a>. %H A378977 Wikipedia, <a href="https://en.wikipedia.org/wiki/Triakis_icosahedron">Triakis icosahedron</a>. %F A378977 Equals arccos(-3*(8 + 5*sqrt(5))/61) = arccos(-3*(8 + 5*A002163)/61). %e A378977 2.8032178560848059621034493264877253281152659880354... %t A378977 First[RealDigits[ArcCos[-3*(8 + 5*Sqrt[5])/61], 10, 100]] (* or *) %t A378977 First[RealDigits[First[PolyhedronData["TriakisIcosahedron", "DihedralAngles"]], 10, 100]] %Y A378977 Cf. A378973 (surface area), A378974 (volume), A378975 (inradius), A378976 (midradius). %Y A378977 Cf. A137218 and A344075 (dihedral angles of a truncated dodecahedron). %Y A378977 Cf. A002163. %K A378977 nonn,cons,easy %O A378977 1,1 %A A378977 _Paolo Xausa_, Dec 14 2024