A389490 Decimal expansion of the largest dihedral angle, in radians, in a biaugmented triangular prism (Johnson solid J_50).

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

Offset

1,1

Comments

This is the dihedral angle between the two adjacent triangular faces at the edge where the two pyramid parts of the solid meet.

Also the analogous dihedral angle in a triaugmented triangular prism (Johnson solid J_51).

Links

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

Polytope Wiki, Biaugmented triangular prism.

Polytope Wiki, Triaugmented triangular prism.

Wikipedia Biaugmented triangular prism.

Wikipedia Triaugmented triangular prism.

Formula

Equals Pi/3 + arccos(-1/3) = A019670 + A156546.

Example

2.9578307874456163024819286661246831365525525231450...

Mathematica

First[RealDigits[Pi/3 + ArcCos[-1/3], 10, 100]] (* or *)
First[RealDigits[Max[PolyhedronData["J50", "DihedralAngles"]], 10, 100]]

Crossrefs

Cf. other J_50 dihedral angles: A019669, A156546, A195702, A387670.

Cf. A385505 (J_50 volume), A384141 (J_50 surface area + 4).

Cf. A019670.

Sequence in context: A375509 A373495 A339925 * A171052 A389041 A021342

Adjacent sequences: A389487 A389488 A389489 * A389491 A389492 A389493

Keyword

nonn,cons,easy

Author

Paolo Xausa, Oct 07 2025

Status

approved