A387297 Decimal expansion of the smallest dihedral angle, in radians, in a gyroelongated triangular cupola (Johnson solid J_22).

1, 7, 2, 6, 1, 2, 0, 6, 6, 2, 2, 9, 4, 6, 7, 3, 4, 6, 9, 4, 2, 6, 9, 4, 3, 4, 0, 3, 0, 9, 7, 0, 5, 0, 2, 7, 7, 3, 4, 1, 4, 6, 8, 6, 9, 1, 0, 5, 3, 9, 0, 3, 0, 8, 3, 9, 4, 4, 9, 7, 0, 3, 7, 0, 0, 6, 3, 8, 6, 5, 2, 6, 3, 0, 5, 3, 7, 5, 7, 7, 6, 1, 8, 6, 8, 7, 5, 4, 7, 7

Offset: 1

Author

Paolo Xausa, Aug 26 2025

Keywords

• nonn
• cons
• easy
• new

Comments

This is the dihedral angle between a triangular face and the hexagonal face.

Examples

			1.7261206622946734694269434030970502773414686910539...
		

Links

• Paolo Xausa, Table of n, a(n) for n = 1..10000
• Wikipedia, Gyroelongated triangular cupola.

Crossrefs

Cf. other J_22 dihedral angles: A195698, A387294, A387295, A387296.

Cf. A344076 (J_22 volume), A344077 (J_22 surface area).

Cf. A010469.

Programs

Mathematica

First[RealDigits[ArcCos[1 - 2/Sqrt[3]], 10, 100]] (* or *)
First[RealDigits[Min[PolyhedronData["J22", "DihedralAngles"]], 10, 100]]

Formula

Equals arccos(1 - 2*sqrt(3)/3) = arccos(1 - A010469/3).