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 A386435 #15 Aug 21 2025 10:00:03 %S A386435 2,4,6,1,9,1,8,8,3,4,6,8,1,5,4,9,3,6,4,2,6,9,8,5,8,3,5,6,4,9,5,9,7,4, %T A386435 7,5,1,4,2,0,6,8,0,0,1,8,7,1,0,1,8,9,6,7,8,1,1,1,0,9,6,6,6,7,3,2,7,9, %U A386435 8,4,6,2,8,9,5,6,5,1,2,1,7,5,7,0,6,5,0,3,2,4 %N A386435 Decimal expansion of the largest dihedral angle, in radians, in a triangular bipyramid (Johnson solid J_12). %C A386435 Also the largest dihedral angle in a triangular orthobicupola (Johnson solid J_27) and the second largest dihedral angle in an augmented truncated tetrahedron (Johnson solid J_65). %H A386435 Paolo Xausa, <a href="/A386435/b386435.txt">Table of n, a(n) for n = 1..10000</a> %H A386435 Wikipedia, <a href="https://en.wikipedia.org/wiki/Augmented_truncated_tetrahedron">Augmented truncated tetrahedron</a>. %H A386435 Wikipedia, <a href="https://en.wikipedia.org/wiki/Triangular_bipyramid">Triangular bipyramid</a>. %H A386435 Wikipedia, <a href="https://en.wikipedia.org/wiki/Triangular_orthobicupola">Triangular orthobicupola</a>. %F A386435 Equals arccos(-7/9). %e A386435 2.461918834681549364269858356495974751420680018710... %t A386435 First[RealDigits[ArcCos[-7/9], 10, 100]] (* or *) %t A386435 First[RealDigits[Max[PolyhedronData["J12", "DihedralAngles"]], 10, 100]] %Y A386435 Cf. A137914 (J_12 smallest dihedral angle). %Y A386435 Cf. A020775 (J_12 volume), A104956 (J_12 surface area). %K A386435 nonn,cons,easy %O A386435 1,1 %A A386435 _Paolo Xausa_, Aug 20 2025