A325111 - OEIS

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A325111

Triangle read by rows: T(n,k) is the number of simple connected graphs on n unlabeled nodes with k articulation vertices, (0 <= k <= n).

1, 1, 0, 1, 0, 0, 1, 1, 0, 0, 3, 2, 1, 0, 0, 10, 7, 3, 1, 0, 0, 56, 33, 17, 5, 1, 0, 0, 468, 244, 101, 32, 7, 1, 0, 0, 7123, 2792, 890, 242, 60, 9, 1, 0, 0, 194066, 52448, 11468, 2461, 527, 97, 12, 1, 0, 0, 9743542, 1690206, 239728, 35839, 6056, 1029, 155, 15, 1, 0, 0

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OFFSET

0,11

COMMENTS

Articulation vertices are also called cutpoints. These are vertices that when removed increase the component count of the graph.

LINKS

Table of n, a(n) for n=0..65.

Eric Weisstein's World of Mathematics, Articulation Vertex

EXAMPLE

Triangle begins:

1 0;

1, 0, 0;