

A066009


Covering numbers C(n,7,6).


3




OFFSET

7,2


COMMENTS

C(v,k,t) is the smallest number of ksubsets of an nset such that every tsubset is contained in at least one of the ksubsets.


REFERENCES

CRC Handbook of Combinatorial Designs, 1996, p. 263.
W. H. Mills and R. C. Mullin, Coverings and packings, pp. 371399 of J. H. Dinitz and D. R. Stinson, editors,a Contemporary Design Theory, Wiley, 1992.


LINKS

Table of n, a(n) for n=7..11.
D. Applegate, E. M. Rains and N. J. A. Sloane, On asymmetric coverings and covering numbers, J. Comb. Des. 11 (2003), 218228.
D. Gordon, La Jolla Repository of Coverings
K. J. Nurmela and P. R. J. Ostergard, New coverings of tsets with (t+1)sets, J. Combinat. Designs, 7 (1999), 217226.
K. J. Nurmela and P. R. J. Ostergard, New coverings of tsets with (t+1)sets (appendix), J. Combinat. Designs, 7 (1999), 217226.
Index entries for covering numbers


CROSSREFS

Cf. A011983. A column of A066010.
Sequence in context: A020941 A024625 A055553 * A037241 A154141 A173661
Adjacent sequences: A066006 A066007 A066008 * A066010 A066011 A066012


KEYWORD

nonn,hard


AUTHOR

N. J. A. Sloane.


STATUS

approved



