

A066225


Covering numbers C(n,n4,n5).


2




OFFSET

6,1


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 Jeffrey H. Dinitz and D. R. Stinson, editors, Contemporary Design Theory, Wiley, 1992.


LINKS

Table of n, a(n) for n=6..14.
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 Patric R. J. Östergård, New coverings of tsets with (t+1)sets, J. Combinat. Designs, 7 (1999), 217226.
K. J. Nurmela and Patric R. J. Östergård, New coverings of tsets with (t+1)sets (appendix), J. Combinat. Designs, 7 (1999), 217226.
Index entries for covering numbers


CROSSREFS

A column of A066010. A036830 is a lower bound.
Sequence in context: A267210 A074988 A265381 * A305777 A139817 A173010
Adjacent sequences: A066222 A066223 A066224 * A066226 A066227 A066228


KEYWORD

nonn,hard


AUTHOR

N. J. A. Sloane


EXTENSIONS

Next term is in range 354357.


STATUS

approved



