A232815 - OEIS

A232815

Decimal expansion of the minimum surface index of a closed cone.

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

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OFFSET

1,1

COMMENTS

Equivalently, minimum surface area among all closed cones enclosing a unit volume. It is attained when the cone is right circular and its height equals the diameter of its base multiplied by sqrt(2). Considering one of the ways of marketing ice cream, we might call it the "frozen cone constant".

For a general definition of surface index, see A232808.

LINKS

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

Wikipedia, Cone

FORMULA

Equals (72*Pi)^(1/3) = 6*(Pi/3)^(1/3).

EXAMPLE

6.0929477853795556034363160089487569369107615150472...

MATHEMATICA

RealDigits[Surd[72*Pi, 3], 10, 120][[1]] (* Harvey P. Dale, Jul 13 2015 *)

CROSSREFS

Cf. Other surface indices: A232808 (spheres), A232809, A232810, A232811, A232812 (platonic solids), A232813 (closed cylinders), A232814 (open cylinders), A232816 (open cones), A232817 (open tubes).

Sequence in context: A331239 A324008 A248681 * A323606 A133077 A200124

Adjacent sequences: A232812 A232813 A232814 * A232816 A232817 A232818

KEYWORD

nonn,cons,easy

AUTHOR

Stanislav Sykora, Dec 04 2013

STATUS

approved