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

Author

Stanislav Sykora, Dec 01 2013

Keywords

• nonn
• cons
• easy

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

Examples

			5.7191057579816194425444539723965629466374425679...
		

Links

• Stanislav Sykora, Table of n, a(n) for n = 1..1000
• Wikipedia, Platonic solid
• Index entries for algebraic numbers, degree 6

Crossrefs

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

Programs

Mathematica

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

PARI

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

Formula

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

A010469/A131594^(2/3).