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A324244
Triangle read by rows: T(n,k) is the number of connected graphs on n nodes with k peripheral nodes.
3
1, 0, 1, 0, 1, 1, 0, 2, 2, 2, 0, 5, 4, 7, 5, 0, 25, 20, 16, 23, 28, 0, 185, 146, 119, 57, 123, 223, 0, 2459, 1728, 1523, 948, 405, 903, 3151, 0, 58156, 36109, 32119, 24637, 13927, 4713, 11746, 79673, 0, 2617378, 1446609, 1304109, 1026845, 723871, 353620, 110734, 279535, 3853870
OFFSET
1,8
COMMENTS
The peripheral nodes of a graph are those with eccentricity equal to the diameter.
LINKS
Eric Weisstein's World of Mathematics, Graph Periphery
EXAMPLE
Triangle begins:
1;
0, 1;
0, 1, 1;
0, 2, 2, 2;
0, 5, 4, 7, 5;
0, 25, 20, 16, 23, 28;
0, 185, 146, 119, 57, 123, 223;
0, 2459, 1728, 1523, 948, 405, 903, 3151;
0, 58156, 36109, 32119, 24637, 13927, 4713, 11746, 79673;
...
CROSSREFS
Row sums give A001349.
Column k=2 is A324263.
Rightmost diagonal is A324264.
Sequence in context: A084203 A073358 A124342 * A082835 A104241 A011139
KEYWORD
nonn,tabl
AUTHOR
Andrew Howroyd, Sep 02 2019
STATUS
approved