A362908 - OEIS

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A362908

Number of graphs on n unlabeled nodes with treewidth 2.

%I #9 May 10 2023 12:47:36

%S 0,0,0,1,4,17,72,323,1639,9203

%N Number of graphs on n unlabeled nodes with treewidth 2.

%H Wikipedia, <a href="http://en.wikipedia.org/wiki/Treewidth">Treewidth</a>.

%e There is a single graph of treewidth 2 on 3 vertices, which is the complete graph.

%o (SageMath) [sum(1 for g in graphs(n) if g.treewidth() == 2) for n in range(9)]

%Y Column 2 of A263294.

%K nonn,more

%O 0,5

%A _Martin Rubey_, May 09 2023