A390428 Decimal expansion of the largest dihedral angle, in radians, in an augmented sphenocorona (Johnson solid J_87).

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

Offset

1,1

Links

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

Wikipedia, Augmented sphenocorona.

Formula

Equals arccos(c), where c = -0.989663... is the smallest real root of 207594140625*x^16 + 408815910000*x^14 + 9390141912816*x^12 - 15859963643328*x^10 + 34091909096544*x^8 - 61482113793792*x^6 + 39304325005056*x^4 - 5961927951360*x^2 + 4722438400.

Example

2.9976840553745135139932759262242896358118193558345...

Mathematica

First[RealDigits[ArcCos[Root[207594140625*#^16 + 408815910000*#^14 + 9390141912816*#^12 - 15859963643328*#^10 + 34091909096544*#^8 - 61482113793792*#^6 + 39304325005056*#^4 - 5961927951360*#^2 + 4722438400 &, 1]], 10, 100]] (* or *)
First[RealDigits[Max[PolyhedronData["J87", "DihedralAngles"]], 10, 100]]

Crossrefs

Cf. other J_87 dihedral angles: A156546, A390281, A390282, A390284, A390285, A390286, A390287, A390288, A390426, A390427.

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

Sequence in context: A087042 A266274 A387989 * A003678 A201683 A331369

Adjacent sequences: A390425 A390426 A390427 * A390429 A390430 A390431

Keyword

nonn,cons,easy

Author

Paolo Xausa, Nov 06 2025

Status

approved