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.
Stanislav Sykora, Table of n, a(n) for n = 1..1000
Wikipedia, Cylinder (geometry)
Equals (16*Pi)^(1/3) = 2*(2*Pi)^(1/3).
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 * A247398 A094560 A179615
Adjacent sequences: A232814 A232815 A232816 * A232818 A232819 A232820
Stanislav Sykora, Dec 05 2013