A386854 Decimal expansion of the largest dihedral angle, in radians, in an elongated triangular pyramid (Johnson solid J_7).

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

Offset

1,1

Comments

Also the largest dihedral angle, in radians, in an elongated triangular bipyramid, elongated pentagonal bipyramid, elongated triangular orthobicupola and elongated triangular gyrobicupola (Johnson solids J_14, J_18, J_35 and J_36, respectively).

Links

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

Wikipedia, Elongated triangular bipyramid.

Wikipedia, Elongated triangular cupola.

Wikipedia, Elongated triangular gyrobicupola.

Wikipedia, Elongated triangular orthobicupola.

Wikipedia, Elongated triangular pyramid.

Index entries for transcendental numbers.

Formula

Equals arccos(-sqrt(8)/3) = arccos(-A010466/3) = arccos(-2*A131594).

Example

2.80175574413567130136625086988773881780892470904...

Mathematica

First[RealDigits[ArcCos[-Sqrt[8]/3], 10, 100]] (* or *)
First[RealDigits[Max[PolyhedronData["J7", "DihedralAngles"]], 10, 100]]

Prog

(PARI) acos(-sqrt(8)/3) \\ Charles R Greathouse IV, Aug 19 2025

Crossrefs

Cf. A010466, A131594.

Sequence in context: A199156 A073001 A088153 * A259173 A010594 A370944

Adjacent sequences: A386851 A386852 A386853 * A386855 A386856 A386857

Keyword

nonn,cons,easy

Author

Paolo Xausa, Aug 06 2025

Status

approved