A380703 Decimal expansion of the obtuse vertex angle, in radians, in a (small) triakis octahedron face.

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

Offset: 1

Author

Paolo Xausa, Jan 30 2025

Keywords

• nonn
• cons
• easy

Examples

			2.045535838349167749400916817638245527237744672...
		

Links

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

Crossrefs

Cf. A380702 (face obtuse angles).

Cf. A010503, A378351, A378352, A378353, A378354.

Programs

Mathematica

First[RealDigits[ArcCos[1/4 - Sqrt[2]/2], 10, 100]]

Formula

Equals arccos(1/4 - sqrt(2)/2) = arccos(1/2 + A010503).

Equals Pi - 2*A380702.