# Greetings from The On-Line Encyclopedia of Integer Sequences! https://backiee.wasmer.app/https_oeis_org/

Search: id:a066009
Showing 1-1 of 1

%I A066009 #16 Feb 10 2026 12:23:38
%S A066009 1,7,16,45,84
%N A066009 Covering numbers C(n,7,6).
%C A066009 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.
%D A066009 CRC Handbook of Combinatorial Designs, 1996, p. 263.
%D A066009 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.
%H A066009 D. Applegate, E. M. Rains and N. J. A. Sloane, <a href="http://arXiv.org/abs/math.CO/0205303">On asymmetric coverings and covering numbers</a>, J. Comb. Des. 11 (2003), 218-228.
%H A066009 D. Gordon, <a href="http://www.dmgordon.org/cover">La Jolla Repository of Coverings</a>.
%H A066009 K. J. Nurmela and Patric R. J. Östergård, <a href="http://www.tcs.hut.fi/old/papers/tp1.ps.Z">New coverings of t-sets with (t+1)-sets</a>, J. Combinat. Designs, 7 (1999), 217-226.
%H A066009 K. J. Nurmela and Patric R. J. Östergård, <a href="http://www.tcs.hut.fi/old/papers/table3_html">New coverings of t-sets with (t+1)-sets (appendix)</a>, J. Combinat. Designs, 7 (1999), 217-226.
%H A066009 Wikipedia, <a href="https://en.wikipedia.org/wiki/Covering_design">Covering design</a>.
%H A066009 <a href="/index/Cor#covnum">Index entries for covering numbers</a>.
%Y A066009 Cf. A011983. A column of A066010.
%K A066009 nonn,hard,more
%O A066009 7,2
%A A066009 _N. J. A. Sloane_

# Content is available under The OEIS End-User License Agreement: https://backiee.wasmer.app/https_oeis_org/LICENSE