what is most special about a given integer?

[Antreas P. Hatzipolakis]

David W. Wilson wrote:

>14: The smallest number of squares that can be placed so that each touches 3
>others at more than a point.

The maximum number of distinct sets that can be generated from one set
in a topological space under the operations of closure and complementation
(iterated in any order) is 14.
(Kazimierz Kuratowski, 1922)


Antreas