A380701 Decimal expansion of the obtuse vertex angle, in radians, in a triakis tetrahedron face.

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

Offset

1,2

Links

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

Wikipedia, Triakis tetrahedron.

Formula

Equals arccos(-7/18).

Equals Pi - 2*A380700.

Example

1.9702215666754913192271283063244673517964472650318...

Mathematica

First[RealDigits[ArcCos[-7/18], 10, 100]]

Crossrefs

Cf. A380700 (face acute angles).

Cf. A378204, A378205, A378206, A378207, A378208.

Sequence in context: A184964 A185364 A085678 * A256687 A086819 A019885

Adjacent sequences: A380698 A380699 A380700 * A380702 A380703 A380704

Keyword

nonn,cons,easy,new

Author

Paolo Xausa, Jan 30 2025

Status

approved