|   | 1 |  initial version  | 
Following the link given by @kcrisman you learn about nauty_geng.
sage: gen = graphs.nauty_geng("9 -c")
sage: sum(1 for g in gen)
261080
 Copyright Sage, 2010. Some rights reserved under creative commons license. Content on this site is licensed under a Creative Commons Attribution Share Alike 3.0 license.
 
                
                Copyright Sage, 2010. Some rights reserved under creative commons license. Content on this site is licensed under a Creative Commons Attribution Share Alike 3.0 license.