[seqfan] Chemistry sequence

[David Wilson]

Maybe this isn't a well defined question, but...

How many molecules have total atomic number n?

There are clearly issues with this question, such as counting 
low-temperature helium compounds. Another problem arises from trying to 
count, say, all the molecular configurations that could be formed from, 
say, 10 carbon atoms. Still, I wonder how far we could go with any 
degree of confidence.