0,2
J. I. Brown and S. Watson, The number of complements of a topology on n points is at least 2^n (except for some special cases), Discr. Math., 154 (1996), 27-39.
Sequence in context: A028389 A041603 A176543 * A063168 A163683 A103090
Adjacent sequences: A018196 A018197 A018198 * A018200 A018201 A018202
nonn
N. J. A. Sloane (njas(AT)research.att.com).