A390637 Decimal expansion of the second largest dihedral angle, in radians, in a sphenomegacorona (Johnson solid J_88).

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

Offset

1,1

Links

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

Polytope Wiki, Sphenomegacorona.

Wikipedia, Sphenomegacorona.

Formula

Equals arccos(c), where c = -0.9482... is the third smallest real root of 490329056390625*x^16 + 28411094140326000*x^15 + 419734516340536344*x^14 + 2644816755210884496*x^13 + 8453051383232766780*x^12 + 12442797810000113904*x^11 - 1822475429326088856*x^10 - 33126428134418768496*x^9 - 36034933983651744858*x^8 + 9918600527585561040*x^7 + 40060741208764305960*x^6 + 15957217777429568304*x^5 - 9663183202520702340*x^4 - 7284536543097238320*x^3 - 1095525886862271528*x^2 - 580784665299904080*x - 316961430445776575.

Example

2.81840740645001578047071670397553161004688142838...

Mathematica

First[RealDigits[ArcCos[Root[490329056390625*#^16 + 28411094140326000*#^15 + 419734516340536344*#^14 + 2644816755210884496*#^13 + 8453051383232766780*#^12 + 12442797810000113904*#^11 - 1822475429326088856*#^10 - 33126428134418768496*#^9 - 36034933983651744858*#^8 + 9918600527585561040*#^7 + 40060741208764305960*#^6 + 15957217777429568304*#^5 - 9663183202520702340*#^4 - 7284536543097238320*#^3 - 1095525886862271528*#^2 - 580784665299904080*# - 316961430445776575 &, 3]], 10, 100]] (* or *)
First[RealDigits[RankedMax[Union[PolyhedronData["J88", "DihedralAngles"]], 2], 10, 100]]

Crossrefs

Cf. other J_88 dihedral angles: A390630, A390631, A390632, A390633, A390634, A390635, A390636, A390638.

Cf. A334114 (J_88 volume), A010502 (J_88 surface area - 2).

Sequence in context: A201763 A254277 A244688 * A086037 A343487 A199787

Adjacent sequences: A390634 A390635 A390636 * A390638 A390639 A390640

Keyword

nonn,cons,easy

Author

Paolo Xausa, Nov 21 2025

Status

approved