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 A387148 #10 Aug 21 2025 16:50:42 %S A387148 2,7,6,7,5,9,9,5,0,1,1,1,6,7,4,7,9,5,9,4,8,6,4,1,9,2,2,5,6,3,7,7,4,1, %T A387148 7,0,6,9,5,2,3,3,1,7,6,6,9,9,2,5,8,9,5,5,7,2,8,0,0,7,3,7,3,9,1,3,5,9, %U A387148 2,7,9,3,3,1,7,7,9,2,7,7,6,3,8,4,6,3,2,8,9,8 %N A387148 Decimal expansion of the largest dihedral angle, in radians, in a gyroelongated square pyramid (Johnson solid J_10). %C A387148 This is the dihedral angle between a triangular face in the square pyramid part and a triangular face in the square antiprism part of the solid. %C A387148 Also the analogous dihedral angle in a gyroelongated square bipyramid (Johnson solid J_17). %H A387148 Paolo Xausa, <a href="/A387148/b387148.txt">Table of n, a(n) for n = 1..10000</a> %H A387148 Wikipedia, <a href="https://en.wikipedia.org/wiki/Gyroelongated_square_bipyramid">Gyroelongated square bipyramid</a>. %H A387148 Wikipedia, <a href="https://en.wikipedia.org/wiki/Gyroelongated_square_pyramid">Gyroelongated square pyramid</a>. %F A387148 Equals arccos((1 - sqrt(2) - 2*2^(1/4))/3) = arccos((1 - A002193 - A011027)/3). %e A387148 2.76759950111674795948641922563774170695233176699... %t A387148 First[RealDigits[ArcCos[(1 - Sqrt[2] - 32^(1/4))/3], 10, 100]] (* or *) %t A387148 First[RealDigits[Max[PolyhedronData["J10", "DihedralAngles"]], 10, 100]] %Y A387148 Cf. other J_10 dihedral angles: A156546, A387149, A387150. %Y A387148 Cf. A179638 (J_10 volume), A374948 (J_10 surface area). %Y A387148 Cf. A002193, A011027. %K A387148 nonn,cons,easy %O A387148 1,1 %A A387148 _Paolo Xausa_, Aug 19 2025