A232811 Decimal expansion of the surface index of a regular octahedron.

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

Offset

1,1

Comments

Equivalently, the surface area of a regular octahedron with unit volume. Among Platonic solids, surface indices decrease with increasing number of faces: A232812 (tetrahedron), 6.0 (cube = hexahedron), this one, A232810 (dodecahedron), and A232809 (icosahedron).

An algebraic integer of degree 6 with minimal polynomial x^6 - 34992. - Charles R Greathouse IV, Apr 25 2016

Links

Stanislav Sykora, Table of n, a(n) for n = 1..1000

Wikipedia, Platonic solid

Index entries for algebraic numbers, degree 6

Formula

sqrt(3)*6^(2/3).

A010469/A131594^(2/3).

Example

5.7191057579816194425444539723965629466374425679...

Mathematica

RealDigits[Sqrt[3]Surd[36, 3], 10, 120][[1]] (* Harvey P. Dale, Mar 12 2015 *)

Prog

(PARI) sqrtn(34992, 6) \\ Charles R Greathouse IV, Apr 25 2016

Crossrefs

Cf. A010469, A131594, A232808 (surface index for a sphere), A232809, A232810, A232812.

Sequence in context: A155066 A343480 A251735 * A316132 A261159 A145737

Adjacent sequences: A232808 A232809 A232810 * A232812 A232813 A232814

Keyword

nonn,cons,easy

Author

Stanislav Sykora, Dec 01 2013

Status

approved