Quandaries and Queries
  


Hello,

I am a student who want to know:
Is there any formula for counting the number of trees (graphs)?



Hi Ali,

If you mean the number of spanning trees of a graph on n labelled points it is due to Cayley and is nn-2.

Denis

Thank you for your answering to my question about trees, but I mean the number of unlabelled trees?

Best regards,
Ali



Hi again Ali,

Go to http://www.research.att.com/~njas/sequences/index.html and enter the sequence

1, 2, 3, 6, 11, 23, 47, 106, 235

Denis


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