A086676 Number of n-dimensional 2 X 2 X ... X 2 grid graphs needed to cover an n-dimensional 3 X 3 X ... X 3 torus.

2, 3, 5, 8, 12, 18, 29, 44, 68

Offset

1,1

References

Patric R. J. Östergård and T. Riihonen, A covering problem for tori, Annals of Combinatorics, 7 (2003), 1-7.

Links

Table of n, a(n) for n=1..9.

D. Brink, The Inverse Football Pool Problem, J. Int. Seq. 14 (2011) # 11.8.8.

Emil Kolev, Covering of {F_3}^n with spheres of maximal radius, Fourteenth International Workshop on Algebraic and Combinatorial Coding Theory, September 7-13, 2014, Svetlogorsk (Kaliningrad region), Russia pp. 198-203.

E. Kolev and T. Baicheva, About the inverse football pool problem for 9 games, Seventh International Workshop on Optimal Codes and Related Topics, September 6-12, 2013, Albena, Bulgaria pp. 125-133.

Patric R. J. Östergård, Home page

Example

Known bounds for n=10 through 13, from Kolev (2014):
10 102-104
11 153-172
12 230-264
13 345-408

Crossrefs

Sequence in context: A018135 A065435 A301750 * A055804 A267372 A369696

Adjacent sequences: A086673 A086674 A086675 * A086677 A086678 A086679

Keyword

nonn

Author

N. J. A. Sloane, Jul 28 2003

Extensions

I have added two terms (29 and 44). The ranges for the next terms are [66,68] and [99,104]. David Brink, Jun 03 2009

For a(9) = 68 and further bounds see Kolev and Baicheva. - N. J. A. Sloane, Mar 10 2014

Status

approved