A390176 Decimal expansion of the second largest dihedral angle, in radians, in a snub square antiprism (Johnson solid J_85).

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

Offset

1,1

Links

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

Polytope Wiki, Snub square antiprism.

Wikipedia, Snub square antiprism.

Formula

Equals arccos(c), where c = -0.8235388... is the second largest negative root of 729*x^12 - 17982*x^10 + 116559*x^8 - 294948*x^6 + 341271*x^4 - 182238*x^2 + 36481.

Example

2.5384178469124103455761297508189241831345523516287...

Mathematica

First[RealDigits[ArcCos[Root[729*#^12 - 17982*#^10 + 116559*#^8 - 294948*#^6 + 341271*#^4 - 182238*#^2 + 36481 &, 5]], 10, 100]] (* or *)
First[RealDigits[RankedMax[Union[PolyhedronData["J85", "DihedralAngles"]], 2], 10, 100]]

Crossrefs

Cf. other J_85 dihedral angles: A390174, A390175, A390177.

Cf. A386696 (J_85 volume), A385259 (J_85 surface area + 8).

Sequence in context: A186631 A359478 A182184 * A115318 A338060 A169856

Adjacent sequences: A390173 A390174 A390175 * A390177 A390178 A390179

Keyword

nonn,cons,easy

Author

Paolo Xausa, Oct 29 2025

Status

approved