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A370073
Triangle read by rows: T(n,k) is the number of unlabeled connected n-vertex graphs that are reachable in k (but no fewer) steps from the empty n-vertex graph, where a step consists of choosing a subset S of the vertices and replacing the subgraph induced by S by its complement, 0 <= k <= n-1.
1
1, 0, 1, 0, 1, 1, 0, 1, 4, 1, 0, 1, 7, 12, 1, 0, 1, 10, 53, 47, 1, 0, 1, 14, 139, 474, 224, 1, 0, 1, 18, 304, 2500, 6670, 1623, 1
OFFSET
1,9
COMMENTS
The intermediate graphs may be disconnected.
See A370072 for further details.
EXAMPLE
Triangle begins:
1;
0, 1;
0, 1, 1;
0, 1, 4, 1;
0, 1, 7, 12, 1;
0, 1, 10, 53, 47, 1;
0, 1, 14, 139, 474, 224, 1;
0, 1, 18, 304, 2500, 6670, 1623, 1;
...
CROSSREFS
Cf. A001349 (row sums), A370072.
Sequence in context: A318623 A332055 A073027 * A278986 A292159 A099793
KEYWORD
nonn,tabl,more
AUTHOR
STATUS
approved