A380861 Decimal expansion of the smallest acute vertex angle, in radians, in a deltoidal hexecontahedron face.

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

Offset: 1

Author

Paolo Xausa, Feb 06 2025

Keywords

• nonn
• cons
• easy

Comments

A deltoidal hexecontahedron face is a kite with one smallest acute angle (this constant), two largest acute angles (A380862) and one obtuse angle (A380863).

Examples

			1.1830367284200834147901361867998878650548206683684...
		

Links

• Paolo Xausa, Table of n, a(n) for n = 1..10000
• Wikipedia, Deltoidal hexecontahedron.

Crossrefs

Cf. A002163, A379385, A379386, A379387, A379388, A379389, A380862, A380863.

Programs

Mathematica

First[RealDigits[ArcCos[(9*Sqrt[5] - 5)/40], 10, 100]]

Formula

Equals arccos((9*sqrt(5) - 5)/40) = arccos((9*A002163 - 5)/40).

Equals 2*Pi - 2*A380862 - A380863.