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A232811 Decimal expansion of the surface index of a regular octahedron. 9
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 (list; constant; graph; refs; listen; history; text; internal format)
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

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

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Last modified November 30 06:28 EST 2021. Contains 349419 sequences. (Running on oeis4.)