cp's OEIS Frontend

A387295 Decimal expansion of the second largest dihedral angle, in radians, in a gyroelongated triangular cupola (Johnson solid J_22).

%I A387295 #10 Sep 02 2025 05:58:24
%S A387295 2,6,8,1,4,3,7,2,8,0,4,1,9,1,8,2,7,4,7,5,9,0,8,0,0,5,0,5,6,1,2,8,0,8,
%T A387295 0,3,1,5,8,4,8,8,3,3,8,6,0,6,3,9,0,8,5,7,4,9,0,4,6,6,8,4,9,9,3,8,5,7,
%U A387295 7,7,3,0,8,9,5,7,7,3,4,2,1,7,2,5,6,1,4,6,3,8
%N A387295 Decimal expansion of the second largest dihedral angle, in radians, in a gyroelongated triangular cupola (Johnson solid J_22).
%C A387295 This is the dihedral angle between a triangular face in the antiprism part of the solid and a square face in the cupola part of the solid.
%C A387295 Also the analogous dihedral angle in a gyroelongated triangular bicupola (Johnson solid J_44).
%H A387295 Paolo Xausa, <a href="/A387295/b387295.txt">Table of n, a(n) for n = 1..10000</a>
%H A387295 Wikipedia, <a href="https://en.wikipedia.org/wiki/Gyroelongated_triangular_bicupola">Gyroelongated triangular bicupola</a>.
%H A387295 Wikipedia, <a href="https://en.wikipedia.org/wiki/Gyroelongated_triangular_cupola">Gyroelongated triangular cupola</a>.
%F A387295 Equals arccos(sqrt(3)/3) + arccos(1 - 2*sqrt(3)/3) = A195696 + arccos(-A246724).
%e A387295 2.6814372804191827475908005056128080315848833860639...
%t A387295 First[RealDigits[ArcTan[Sqrt[2]] + ArcCos[1 - Sqrt[12]/3], 10, 100]] (* or *)
%t A387295 First[RealDigits[RankedMax[Union[PolyhedronData["J22", "DihedralAngles"]], 2], 10, 100]]
%Y A387295 Cf. other J_22 dihedral angles: A195698, A387294, A387296, A387297.
%Y A387295 Cf. A344076 (J_22 volume), A344077 (J_22 surface area).
%Y A387295 Cf. A385256 (J_44 volume), A385257 (J_44 surface area).
%Y A387295 Cf. A195696, A246724.
%K A387295 nonn,cons,easy,new
%O A387295 1,1
%A A387295 _Paolo Xausa_, Aug 25 2025