My question is about (abstract) simplicial complices. In particular, how many are they if I consider $n$ unlabelled vertices? For example, if $n=4$, the two complices $$ \{\varnothing, \{1\}, \{2\}, \{3\}, \{4\}, \{1, 2\}, \{3, 4\}\} $$ and $$ \{\varnothing, \{1\}, \{2\}, \{3\}, \{4\}, \{2, 3\}, \{1, 4\}\} $$ are the same, but not $$ \{\varnothing, \{1\}, \{2\}, \{3\}, \{4\}, \{1, 2\}, \{1, 3\}\} $$ (since the last two sides of this one intersect in one vertex). If $n=3$, there are 5 of them (while the Dedekind number for 3 is 20). They are: - dim=2 $$\{\varnothing, \{1\}, \{2\}, \{3\}, \{1, 2\}, \{1, 3\}, \{2, 3\}, \{1, 2, 3\}\}$$ - dim=1 $$\{\varnothing, \{1\}, \{2\}, \{3\}, \{1, 2\}, \{1, 3\}, \{2, 3\}\}$$ $$\{\varnothing, \{1\}, \{2\}, \{3\}, \{1, 2\}, \{1, 3\}\}$$ $$\{\varnothing, \{1\}, \{2\}, \{3\}, \{1, 2\}\}$$ - dim 0 $$\{\varnothing, \{1\}, \{2\}, \{3\}\}$$ Since this last observation, I think that the answer is not the Dedekind number, but please prove me wrong if you think it is. Thank you in advance, Davide PS: I am not sure whether or not this question is related to [this other one](http://mathoverflow.net/q/102587/42995). If so, please can you explain why? PPS: I posted this question also [on Math.SE](http://math.stackexchange.com/q/896042/110046), but no one answered.