A232817 - OEIS

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A232817

Decimal expansion of the open-tube surface index constant.

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

(list; constant; graph; refs; listen; history; text; internal format)

OFFSET

1,1

COMMENTS

The external surface index of an open-ended cylinder (tube) equals this constant, multiplied by (Length/Diameter)^(1/3).

For a general definition of surface index, see A232808.

LINKS

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

Wikipedia, Cylinder (geometry).

FORMULA

Equals (16*Pi)^(1/3) = 2*(2*Pi)^(1/3).

MATHEMATICA

RealDigits[2 * Surd[2 * Pi, 3], 10, 120][[1]] (* Amiram Eldar, May 17 2023 *)

CROSSREFS

Cf. Other surface indices: A232808 (spheres), A232809, A232810, A232811, A232812 (platonic solids), A232813 (closed cylinders), A232814 (open cylinders), A232815 (closed cones), A232816 (open cones).

Sequence in context: A021275 A281802 A197292 * A346640 A247398 A094560

Adjacent sequences: A232814 A232815 A232816 * A232818 A232819 A232820

KEYWORD

nonn,cons,easy

AUTHOR

Stanislav Sykora, Dec 05 2013

STATUS

approved