A390978 Decimal expansion of the fourth smallest dihedral angle, in radians, in a hebesphenomegacorona (Johnson solid J_89).

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

Offset

1,1

Links

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

Polytope Wiki, Hebesphenomegacorona.

Wikipedia, Hebesphenomegacorona.

Formula

Equals arccos(c), where c = -0.69431686... is the third smallest real root of 26873856*x^20 - 127930752*x^18 + 235415241*x^16 - 200232000*x^14 + 79688448*x^12 - 58696704*x^10 + 111532032*x^8 - 105971712*x^6 + 49807360*x^4 - 11534336*x^2 + 1048576.

Example

2.3382665558600765877217610013543475144732326470597...

Mathematica

First[RealDigits[ArcCos[Root[26873856*#^20 - 127930752*#^18 + 235415241*#^16 - 200232000*#^14 + 79688448*#^12 - 58696704*#^10 + 111532032*#^8 - 105971712*#^6 + 49807360*#^4 - 11534336*#^2 + 1048576 &, 3]], 10, 100]] (* or *)
First[RealDigits[RankedMin[Union[PolyhedronData["J89", "DihedralAngles"]], 4], 10, 100]]

Crossrefs

Cf. other J_89 dihedral angles: A390975, A390976, A390977, A390979, A390980, A390981, A390982.

Cf. A386741 (J_89 volume), A386742 (J_89 surface area).

Sequence in context: A127582 A157144 A096714 * A078035 A295725 A132822

Adjacent sequences: A390975 A390976 A390977 * A390979 A390980 A390981

Keyword

nonn,cons,easy

Author

Paolo Xausa, Nov 28 2025

Status

approved