Number of (connected/unrestricted) n-vertex subgraphs of the undirected complete graph on n vertices, up to isomorphism. Starting at n = 0, I'm thinking these begin: connected: 1,1,1,2,6,... unrestricted: 1,1,2,4,11,... Not sure if these are already in the OEIS. Also, I counted by hand, so I could be wrong on the counts.