

A322754


Number of unlabeled 7trees on n nodes


0



0, 0, 0, 0, 0, 0, 1, 1, 1, 2, 5, 15, 64, 342, 2344, 19137, 181098, 1922215, 22472875, 284556458, 3849828695, 54974808527, 819865209740, 12655913153775, 200748351368185, 3253193955012557, 53619437319817482, 895778170144927928, 15129118461773051724
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OFFSET

1,10


COMMENTS

A ktree is recursively defined as follows: K_k is a ktree and any ktree on n+1 vertices is obtained by joining a vertex to a kclique in a ktree on n vertices.


REFERENCES

Miklos Bona, editor, Handbook of Enumerative Combinatorics, CRC Press, 2015, page 328.


LINKS

Table of n, a(n) for n=1..29.
Andrew GainerDewar, GammaSpecies and the Enumeration of kTrees, Electronic Journal of Combinatorics, Volume 19 (2012), #P45.


CROSSREFS

Cf. A054581 (unlabeled 2trees), A078792 (unlabeled 3trees), A078793 (unlabeled 4trees), A201702 (unlabeled 5trees), A202037 (unlabeled 6trees).
Sequence in context: A078793 A201702 A202037 * A224917 A274100 A166355
Adjacent sequences: A322751 A322752 A322753 * A322755 A322756 A322757


KEYWORD

nonn


AUTHOR

N. J. A. Sloane, Dec 26 2018


STATUS

approved



