This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A222066 #26 Dec 30 2023 09:51:47
%S A222066 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,
%T A222066 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,
%U A222066 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
%N A222066 Decimal expansion of 1/sqrt(128).
%C A222066 Conjectured to be center density of densest packing of equal spheres in five dimensions (achieved for example by the D_5 lattice).
%D A222066 J. H. Conway and N. J. A. Sloane, "Sphere Packings, Lattices and Groups", Springer, 3rd. ed., 1998. See p. xix.
%H A222066 J. H. Conway and N. J. A. Sloane, <a href="https://doi.org/10.1007/BF02574051">What are all the best sphere packings in low dimensions?</a>, Discr. Comp. Geom., 13 (1995), 383-403.
%H A222066 G. Nebe and N. J. A. Sloane, <a href="http://www.math.rwth-aachen.de/~Gabriele.Nebe/LATTICES/D5.html">Home page for D_5 lattice</a>
%H A222066 N. J. A. Sloane and Andrey Zabolotskiy, <a href="/A093825/a093825_1.txt">Table of maximal density of a packing of equal spheres in n-dimensional Euclidean space (some values are only conjectural)</a>.
%H A222066 <a href="/index/Al#algebraic_02">Index entries for algebraic numbers, degree 2</a>
%F A222066 Equals A020789/2. - _R. J. Mathar_, Jan 27 2021
%e A222066 .088388347648318440550105545263106129910604492211...
%t A222066 Join[{0},RealDigits[1/Sqrt[128],10,120][[1]]] (* _Harvey P. Dale_, Sep 20 2023 *)
%o A222066 (PARI) 1/sqrt(128) \\ _Charles R Greathouse IV_, Oct 31 2014
%Y A222066 Related constants: A020769, A020789, A093766, A093825, A222067, A222068, A222069, A222070, A222071, A222072, A260646.
%K A222066 nonn,cons
%O A222066 0,2
%A A222066 _N. J. A. Sloane_, Feb 10 2013