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A066225 Covering numbers C(n,n-4,n-5). 2
3, 7, 14, 30, 50, 84, 126, 185, 259 (list; graph; refs; listen; history; text; internal format)
OFFSET

6,1

COMMENTS

C(v,k,t) is the smallest number of k-subsets of an n-set such that every t-subset is contained in at least one of the k-subsets.

REFERENCES

CRC Handbook of Combinatorial Designs, 1996, p. 263.

W. H. Mills and R. C. Mullin, Coverings and packings, pp. 371-399 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), 218-228.

D. Gordon, La Jolla Repository of Coverings

K. J. Nurmela and Patric R. J. Östergård, New coverings of t-sets with (t+1)-sets, J. Combinat. Designs, 7 (1999), 217-226.

K. J. Nurmela and Patric R. J. Östergård, New coverings of t-sets with (t+1)-sets (appendix), J. Combinat. Designs, 7 (1999), 217-226.

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 354-357.

STATUS

approved

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Last modified August 11 06:25 EDT 2020. Contains 336422 sequences. (Running on oeis4.)