cp's OEIS Frontend

A387320 Decimal expansion of the largest dihedral angle, in radians, in a gyroelongated square cupola (Johnson solid J_23).

%I A387320 #14 Sep 02 2025 04:01:18
%S A387320 2,6,8,7,1,5,0,5,0,5,6,3,7,0,7,0,6,2,2,0,5,8,2,3,7,6,7,1,0,3,4,2,1,7,
%T A387320 8,7,2,4,0,8,0,9,4,2,4,3,7,8,8,1,6,0,5,3,3,1,8,5,9,1,6,8,3,2,2,7,7,2,
%U A387320 3,2,9,7,1,2,7,7,5,0,1,0,3,2,5,2,6,9,7,3,5,8
%N A387320 Decimal expansion of the largest dihedral angle, in radians, in a gyroelongated square cupola (Johnson solid J_23).
%C A387320 This is the dihedral angle between triangular faces in the antiprism part of the solid.
%C A387320 Also the analogous dihedral angle in a gyroelongated square bicupola (Johnson solid J_45).
%H A387320 Paolo Xausa, <a href="/A387320/b387320.txt">Table of n, a(n) for n = 1..10000</a>
%H A387320 Polytope Wiki, <a href="https://polytope.miraheze.org/wiki/Gyroelongated_square_bicupola">Gyroelongated square bicupola</a>.
%H A387320 Polytope Wiki, <a href="https://polytope.miraheze.org/wiki/Gyroelongated_square_cupola">Gyroelongated square cupola</a>.
%H A387320 Wikipedia, <a href="https://en.wikipedia.org/wiki/Gyroelongated_square_bicupola">Gyroelongated square bicupola</a>.
%H A387320 Wikipedia, <a href="https://en.wikipedia.org/wiki/Gyroelongated_square_cupola">Gyroelongated square cupola</a>.
%F A387320 Equals arccos((1 - 2*sqrt(2 + sqrt(2)))/3) = arccos((1 - 2*sqrt(2 + A002193))/3).
%e A387320 2.687150505637070622058237671034217872408094243788...
%t A387320 First[RealDigits[ArcCos[(1 - Sqrt[8 + Sqrt[32]])/3], 10, 100]] (* or *)
%t A387320 First[RealDigits[Max[PolyhedronData["J23", "DihedralAngles"]], 10, 100]]
%Y A387320 Cf. other J_23 dihedral angles: A177870, A195702, A387321, A387322, A387323.
%Y A387320 Cf. A384214 (J_23 volume), A384215 (J_23 surface area).
%Y A387320 Cf. A385258 (J_45 volume), A385259 (J_45 surface area).
%Y A387320 Cf. A002193.
%K A387320 nonn,cons,easy,new
%O A387320 1,1
%A A387320 _Paolo Xausa_, Aug 27 2025