A222066 Decimal expansion of 1/sqrt(128).

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

Offset

0,2

Comments

Conjectured to be center density of densest packing of equal spheres in five dimensions (achieved for example by the D_5 lattice).

References

J. H. Conway and N. J. A. Sloane, "Sphere Packings, Lattices and Groups", Springer, 3rd. ed., 1998. See p. xix.

Links

Table of n, a(n) for n=0..104.

J. H. Conway and N. J. A. Sloane, What are all the best sphere packings in low dimensions?, Discr. Comp. Geom., 13 (1995), 383-403.

G. Nebe and N. J. A. Sloane, Home page for D_5 lattice

N. J. A. Sloane and Andrey Zabolotskiy, Table of maximal density of a packing of equal spheres in n-dimensional Euclidean space (some values are only conjectural).

Index entries for algebraic numbers, degree 2

Formula

Equals A020789/2. - R. J. Mathar, Jan 27 2021

Example

.088388347648318440550105545263106129910604492211...

Mathematica

Join[{0}, RealDigits[1/Sqrt[128], 10, 120][[1]]] (* Harvey P. Dale, Sep 20 2023 *)

Prog

(PARI) 1/sqrt(128) \\ Charles R Greathouse IV, Oct 31 2014

Crossrefs

Related constants: A020769, A020789, A093766, A093825, A222067, A222068, A222069, A222070, A222071, A222072, A260646.

Sequence in context: A254291 A219300 A200686 * A303617 A296428 A073447

Adjacent sequences: A222063 A222064 A222065 * A222067 A222068 A222069

Keyword

nonn,cons

Author

N. J. A. Sloane, Feb 10 2013

Status

approved