0,3

A cover of a set is a T_0-cover if for every two distinct points of the set there exists a member (block) of the cover containing one but not the other point.

Vladeta Jovovic, T_0-covers of a labeled 3-set

a(n)=Sum_{i=0..n+1} stirling1(n+1, i)*2^(2^(i-1)-1).

Cf. A003465, row sums of A059202, A059203, A059084-A059089.

Sequence in context: A111637 A027872 A098695 this_sequence A027638 A041275 A024384

Adjacent sequences: A059198 A059199 A059200 this_sequence A059202 A059203 A059204

easy,nonn

Vladeta Jovovic, Goran Kilibarda (vladeta(AT)Eunet.yu), Jan 16 2001