A378208 Decimal expansion of the dihedral angle, in radians, between any two adjacent faces in a triakis tetrahedron.

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

Offset

1,1

Comments

The triakis tetrahedron is the dual polyhedron of the truncated tetrahedron.

Links

Table of n, a(n) for n=1..90.

Wikipedia, Triakis tetrahedron.

Formula

Equals arccos(-7/11).

Example

2.2605713275803962793413578116086559655552841805381...

Mathematica

First[RealDigits[ArcCos[-7/11], 10, 100]] (* or *)
First[RealDigits[First[PolyhedronData["TriakisTetrahedron", "DihedralAngles"]], 10, 100]]

Crossrefs

Cf. A378204 (surface area), A378205 (volume), A378206 (inradius), A378207 (midradius).

Cf. A137914 and A156546 (dihedral angles of a truncated tetrahedron).

Sequence in context: A011144 A127649 A274440 * A199220 A047916 A101207

Adjacent sequences: A378205 A378206 A378207 * A378209 A378210 A378211

Keyword

nonn,cons,easy

Author

Paolo Xausa, Nov 21 2024

Status

approved