5,2

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.

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

De Caen, D.; Kreher, D. L.; Radziszowski, S. P.; and Mills, W. H., On the covering of t-sets with (t+1)-sets: C(9,5,4) and C(10,6,5). Discrete Math. 92 (1991), no. 1-3, 65-77.

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.

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

Cf. A066009. A column of A066010.

Sequence in context: A060161 A082674 A102172 this_sequence A087940 A092387 A160720

Adjacent sequences: A011980 A011981 A011982 this_sequence A011984 A011985 A011986

nonn,hard

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

Next term is <= 157.