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 A387150 #7 Aug 19 2025 12:29:37 %S A387150 1,8,1,2,2,8,2,8,8,2,9,9,2,2,3,8,6,8,1,3,2,2,5,6,2,1,2,3,1,2,1,9,8,3, %T A387150 9,5,2,7,0,8,9,1,7,0,7,1,9,8,2,5,8,4,0,6,6,3,2,0,3,7,5,6,0,9,8,1,4,0, %U A387150 1,5,8,8,7,2,7,3,9,5,1,3,0,8,4,5,8,9,3,7,3,8 %N A387150 Decimal expansion of the smallest dihedral angle, in radians, in a gyroelongated square pyramid (Johnson solid J_10). %C A387150 This is the dihedral angle between the square face and a triangular face. %H A387150 Paolo Xausa, <a href="/A387150/b387150.txt">Table of n, a(n) for n = 1..10000</a> %H A387150 Wikipedia, <a href="https://en.wikipedia.org/wiki/Gyroelongated_square_pyramid">Gyroelongated square pyramid</a>. %F A387150 Equals arccos(-sqrt(1 - 2*sqrt(2)/3)) = arccos(-sqrt(1 - A010466/3)). %e A387150 1.81228288299223868132256212312198395270891707198... %t A387150 First[RealDigits[ArcCos[-Sqrt[1 - Sqrt[8]/3]], 10, 100]] (* or *) %t A387150 First[RealDigits[Min[PolyhedronData["J10", "DihedralAngles"]], 10, 100]] %Y A387150 Cf. other J_10 dihedral angles: A156546, A387148, A387149. %Y A387150 Cf. A179638 (J_10 volume), A374948 (J_10 surface area). %Y A387150 Cf. A010466. %K A387150 nonn,cons,easy %O A387150 1,2 %A A387150 _Paolo Xausa_, Aug 19 2025