A390427 Decimal expansion of the second largest dihedral angle, in radians, in an augmented sphenocorona (Johnson solid J_87).

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

Offset

1,1

Links

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

Wikipedia, Augmented sphenocorona.

Formula

Equals arccos(c), where c = -0.96250... is the smallest real root of 18225*x^8 - 19440*x^7 - 6048*x^6 + 31680*x^5 + 14304*x^4 - 34560*x^3 - 12800*x^2 + 23552*x - 5888.

Example

2.8668716154998968060913545039786548565952591682940...

Mathematica

First[RealDigits[ArcCos[Root[18225*#^8 - 19440*#^7 - 6048*#^6 + 31680*#^5 + 14304*#^4 - 34560*#^3 - 12800*#^2 + 23552*# - 5888 &, 1]], 10, 100]] (* or *)
First[RealDigits[RankedMax[Union[PolyhedronData["J87", "DihedralAngles"]], 2], 10, 100]]

Crossrefs

Cf. other J_87 dihedral angles: A156546, A390281, A390282, A390284, A390285, A390286, A390287, A390288, A390426, A390428.

Cf. A386740 (J_87 volume), A010502 (J_87 surface area - 1).

Sequence in context: A021890 A390177 A199504 * A368645 A019914 A065473

Adjacent sequences: A390424 A390425 A390426 * A390428 A390429 A390430

Keyword

nonn,cons,easy

Author

Paolo Xausa, Nov 06 2025

Status

approved