A390282 Decimal expansion of the second smallest dihedral angle, in radians, in a sphenocorona (Johnson solid J_86).

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

Offset

1,2

Comments

Also a dihedral angle in an augmented sphenocorona (Johnson solid J_87).

Links

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

Polytope Wiki, Sphenocorona.

Wikipedia, Sphenocorona.

Index entries for transcendental numbers

Formula

Equals arccos(c), where c = -sqrt(298 - 72*sqrt(6) - 4*sqrt(538 + 18*sqrt(6)))/15 = -0.3342022... is the largest negative root of 18225*x^8 - 96552*x^6 + 163224*x^4 - 92832*x^2 + 8464.

Example

1.9115549973753875279274974014628971023518444732840...

Mathematica

First[RealDigits[ArcCos[-Sqrt[298 - 72*Sqrt[6] - 4*Sqrt[538 + 18*Sqrt[6]]]/15], 10, 100]] (* or *)
First[RealDigits[RankedMin[Union[PolyhedronData["J86", "DihedralAngles"]], 2], 10, 100]]

Crossrefs

Cf. other J_86 dihedral angles: A390281, A390283, A390284, A390285, A390286, A390287, A390288.

Cf. A386739 (J_86 volume), A010482 (J_86 surface area - 2).

Sequence in context: A198551 A010162 A228409 * A230155 A072224 A296547

Adjacent sequences: A390279 A390280 A390281 * A390283 A390284 A390285

Keyword

nonn,cons,easy

Author

Paolo Xausa, Nov 03 2025

Status

approved