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 A387323 #11 Sep 02 2025 04:01:32 %S A387323 1,6,8,5,8,9,2,3,8,2,2,4,9,5,3,0,2,6,5,8,5,7,5,9,3,9,5,0,3,3,5,3,7,8, %T A387323 0,7,8,4,3,6,4,5,6,9,8,3,2,4,4,8,2,4,0,3,5,3,1,5,3,5,5,6,1,5,3,0,2,6, %U A387323 1,3,3,2,5,4,7,4,9,8,6,2,4,4,6,6,4,6,8,3,8,3 %N A387323 Decimal expansion of the smallest dihedral angle, in radians, in a gyroelongated square cupola (Johnson solid J_23). %C A387323 This is the dihedral angle between a triangular face and the octagonal face. %H A387323 Paolo Xausa, <a href="/A387323/b387323.txt">Table of n, a(n) for n = 1..10000</a> %H A387323 Polytope Wiki, <a href="https://polytope.miraheze.org/wiki/Gyroelongated_square_cupola">Gyroelongated square cupola</a>. %H A387323 Wikipedia, <a href="https://en.wikipedia.org/wiki/Gyroelongated_square_cupola">Gyroelongated square cupola</a>. %F A387323 Equals arccos(-sqrt((7 + 4*sqrt(2) - 2*sqrt(20 + 14*sqrt(2)))/3)) = arccos(-sqrt((7 + A010487 - 2*sqrt(20 + 14*A002193))/3)). %F A387323 Equals A387321 - A195696 = A387322 - A003881. %e A387323 1.6858923822495302658575939503353780784364569832448... %t A387323 First[RealDigits[ArcCos[-Sqrt[(7 + Sqrt[32] - 2*Sqrt[20 + 14*Sqrt[2]])/3]], 10, 100]] (* or *) %t A387323 First[RealDigits[Min[PolyhedronData["J23", "DihedralAngles"]], 10, 100]] %Y A387323 Cf. other J_23 dihedral angles: A177870, A195702, A387320, A387321, A387322. %Y A387323 Cf. A384214 (J_23 volume), A384215 (J_23 surface area). %Y A387323 Cf. A002193, A003881, A010487, A195696. %K A387323 nonn,cons,easy,new %O A387323 1,2 %A A387323 _Paolo Xausa_, Aug 29 2025