A380863 Decimal expansion of the obtuse vertex angle, in radians, in a deltoidal hexecontahedron face.

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

Offset: 1

Author

Paolo Xausa, Feb 07 2025

Keywords

• nonn
• cons
• easy

Comments

A deltoidal hexecontahedron face is a kite with one smallest acute angle (A380861), two largest acute angles (A380862) and one obtuse angle (this constant).

Examples

			2.0641778238390721349307678649869730069970513653...
		

Links

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

Crossrefs

Cf. A002163, A379385, A379386, A379387, A379388, A379389, A380861, A380862.

Programs

Mathematica

First[RealDigits[ArcCos[(-5 - 2*Sqrt[5])/20], 10, 100]]

Formula

Equals arccos((-5 - 2*sqrt(5))/20) = arccos((-5 - 2*A002163)/20).

Equals 2*Pi - A380861 - 2*A380862.