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A066140 Covering numbers C(n,n-3,n-4). 1
3, 6, 12, 20, 30, 45, 63, 84 (list; graph; refs; listen; history; internal format)
OFFSET

5,1

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

LINKS

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

A column of A066010.

Sequence in context: A180622 A125851 A160732 * A200067 A061061 A001975

Adjacent sequences:  A066137 A066138 A066139 * A066141 A066142 A066143

KEYWORD

nonn

AUTHOR

N. J. A. Sloane (njas(AT)research.att.com).

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Last modified February 14 23:53 EST 2012. Contains 205689 sequences.