A378389 - OEIS

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

(list; constant; graph; refs; listen; history; text; internal format)

OFFSET

1,1

COMMENTS

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

LINKS

Paolo Xausa, Table of n, a(n) for n = 1..10000

Wikipedia, Tetrakis hexahedron.

FORMULA

Equals arccos(-4/5).

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

EXAMPLE

2.498091544796508851659834154562180246155658808...

MATHEMATICA

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

First[RealDigits[First[PolyhedronData["TetrakisHexahedron", "DihedralAngles"]], 10, 100]]

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.

Sequence in context: A241473 A055858 A141389 * A348059 A076125 A011033

Adjacent sequences: A378381 A378383 A378388 * A378400 A378402 A378403

KEYWORD

nonn,cons,easy,new

AUTHOR

Paolo Xausa, Nov 27 2024

STATUS

approved