A378389 Decimal expansion of the dihedral angle, in radians, between any two adjacent faces in a tetrakis hexahedron.

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

Offset: 1

Author

Paolo Xausa, Nov 27 2024

Keywords

• nonn
• cons
• easy

Comments

The tetrakis hexahedron is the dual polyhedron of the truncated octahedron.

Examples

			2.498091544796508851659834154562180246155658808...
		

Links

• Paolo Xausa, Table of n, a(n) for n = 1..10000
• Wikipedia, Tetrakis hexahedron.

Crossrefs

Cf. A378388 (surface area), A374359 (volume - 1), A010532 (inradius*10), A179587 (midradius + 1).

Cf. A156546 and A195698 (dihedral angles of a truncated octahedron), A195729.

Programs

Mathematica

First[RealDigits[ArcCos[-4/5], 10, 100]] (* or *)
First[RealDigits[First[PolyhedronData["TetrakisHexahedron", "DihedralAngles"]], 10, 100]]

Formula

Equals arccos(-4/5).

Equals 2*A195729. - Amiram Eldar, Nov 27 2024