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A336544 Sum over all unlabeled graphs of order n, of the number of graphs obtainable by deletion of a single vertex in the graph. 2
1, 2, 6, 20, 90, 544, 5096, 79220, 2208158, 113737744, 10926144928 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

For a graph G with n vertices, consider deleting each vertex in turn (along with any associated edges). The resulting graphs will have n-1 vertices. Count the distinct graphs reached. This sequence gives the sum of this count over all graphs with n vertices.

LINKS

Table of n, a(n) for n=1..11.

Sean A. Irvine, Illustration of initial terms

Sean A. Irvine, Java program (github)

CROSSREFS

Cf. A336545 (connected graphs).

Sequence in context: A079468 A124382 A318813 * A000666 A180890 A027321

Adjacent sequences:  A336541 A336542 A336543 * A336545 A336546 A336547

KEYWORD

nonn,more

AUTHOR

Sean A. Irvine, Jul 25 2020

STATUS

approved

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Last modified October 25 17:13 EDT 2021. Contains 348255 sequences. (Running on oeis4.)