A380794 Decimal expansion of the obtuse vertex angle, in radians, in a triakis icosahedron face.

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

Offset

1,1

Comments

A triakis icosahedron face is an isoscele triangle with two acute angles (A380793) and one obtuse angle (this constant).

Links

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

Eric Weisstein's World of Mathematics, Triakis Icosahedron.

Wikipedia, Triakis icosahedron.

Formula

Equals arccos(-3*A001622/10).

Equals Pi - 2*A380793.

Example

2.077628612105861047184226260694853007668786641...

Mathematica

First[RealDigits[ArcCos[-3*GoldenRatio/10], 10, 100]]

Crossrefs

Cf. A001622, A378973, A378974, A378976, A378977, A380793.

Sequence in context: A113319 A298749 A021832 * A352615 A377557 A160509

Adjacent sequences: A380791 A380792 A380793 * A380795 A380796 A380797

Keyword

nonn,cons,easy

Author

Paolo Xausa, Feb 04 2025

Status

approved