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A066009 Covering numbers C(n,7,6). 3
1, 7, 16, 45, 84 (list; graph; refs; listen; history; text; internal format)
OFFSET

7,2

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 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), 218-228.

D. Gordon, La Jolla Repository of Coverings

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

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

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

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Last modified February 21 12:27 EST 2018. Contains 299411 sequences. (Running on oeis4.)