Trees

The data available here is basically a copy (as of 2010-07-13) of the data available at Gordon Royle's web page (c) 1999 Gordon Royle.

The graph lists are currently only available in 'graph6' format.

These trees can be generated by using the program FreeTree (see [1]).

Vertices No. of trees
1 1
2 1
3 1
4 2
5 3
6 6
7 11
8 23
9 47
10 106
11 235
12 551
13 1301
14 3159
15 7741
16 19320
17 48629
18 123867
19 317955
20 823065

References

[1] G. Li and F. Ruskey, The advantages of forward thinking in generating rooted and free trees. pp. 939-940. 10th Annual ACM-SIAM Symposium on Discrete Algorithms (SODA), 1999.