A390143 Decimal expansion of the smallest dihedral angle, in radians, in a snub disphenoid (Johnson solid J_84).

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

Offset

1,2

Links

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

Polytope Wiki, Snub disphenoid.

Wikipedia, Snub disphenoid.

Formula

Equals arccos(c/3), where c is the largest root of x^3 + 25*x^2 + 79*x + 23.

Example

1.6789775749362604980287408653316751544832594225595...

Mathematica

First[RealDigits[ArcCos[Root[#^3 + 25*#^2 + 79*# + 23 &, 3]/3], 10, 100]] (* or *)
First[RealDigits[Min[PolyhedronData["J84", "DihedralAngles"]], 10, 100]]

Crossrefs

Cf. other J_84 dihedral angles: A390144, A390145.

Cf. A386695 (J_84 volume), A010482 (J_84 surface area).

Sequence in context: A335094 A153604 A324031 * A248418 A168679 A102304

Adjacent sequences: A390140 A390141 A390142 * A390144 A390145 A390146

Keyword

nonn,cons,easy

Author

Paolo Xausa, Oct 28 2025

Status

approved