A236367 Dihedral angle in a regular icosahedron (radians).

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

Offset

1,1

Links

Stanislav Sykora, Table of n, a(n) for n = 1..2000

Wikipedia, Platonic solid.

Formula

Equals 2*arctan(phi^2) = 2*arctan(A001622^2) = 2*arctan((3+sqrt(5))/2).

Example

2.41186499736282687500784672346618218880066348532739213...

Mathematica

RealDigits[2 * ArcTan[GoldenRatio^2], 10, 120][[1]] (* Amiram Eldar, May 17 2023 *)

Prog

(PARI) 2*atan((3+sqrt(5))/2)

Crossrefs

Cf. A001622, Platonic solids dihedral angles: A137914 (tetrahedron), A156546 (octahedron), A019669 (cube), A137218 (dodecahedron).

Sequence in context: A329458 A332010 A201287 * A197489 A297966 A103161

Adjacent sequences: A236364 A236365 A236366 * A236368 A236369 A236370

Keyword

nonn,cons,easy

Author

Stanislav Sykora, Jan 23 2014

Status

approved