A011977 - OEIS

%I #14 Jan 10 2024 20:27:28

%S 1,3,3,4,5,6,7,9,10,12,13,15,16,18,19,21,21,27,28,30,30,37,38,40

%N Covering numbers C(n,5,2).

%C It is known that 42 <= a(29) <= 43. The next few values are known: a(30) = 48, a(31) = 50, a(32) = 52. - _Nathaniel Johnston_, Jan 10 2024

%D CRC Handbook of Combinatorial Designs, 1996, p. 262.

%H D. Gordon, <a href="http://www.dmgordon.org/cover">La Jolla Repository of Coverings</a>

%H Uenal Mutlu (uenalm(AT)metronet.de), <a href="http://www.tuco.de/math1.htm">Tables of coverings</a>

%H <a href="/index/Cor#covnum">Index entries for covering numbers</a>

%Y Cf. A011975, A240116.

%K nonn,hard

%O 5,2

%A _N. J. A. Sloane_.

%E a(28) from _Nathaniel Johnston_, Jan 10 2024