id:A136795 - OEIS Search Results

Search: id:A136795

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Number of unlabeled marked trees with n nodes.

+0
2

2, 6, 20, 112, 662, 4596, 34032, 268280, 2201634, 18679362, 162611904, 1446148032, 13090979394, 120303384120, 1119971272340, 10544483234056, 100261309326082, 961692928106614, 9296529143261548, 90497666895840376 (list; graph; listen)

	OFFSET	`1,1`
	COMMENT	`A marked tree is a tree where each node and edge is marked as + or -.`
	REFERENCES	`F. Bergeron, G. Labelle and P. Leroux, Combinatorial Species and Tree-Like Structures, Cambridge, 1998, pg 293 (4.1.60)`
	LINKS	`Index entries for sequences related to trees`
	FORMULA	`G.f.: B(x) - B(x)^2 + B(x^2) where B(x) is g.f. of A136794.`
	CROSSREFS	`Cf. A136794 (rooted tree version), A136797 (labeled version).` `Adjacent sequences: A136792 A136793 A136794 this_sequence A136796 A136797 A136798` `Sequence in context: A052433 A078566 A076323 this_sequence A074115 A013206 A073966`
	KEYWORD	`nonn`
	AUTHOR	`Christian G. Bower (bowerc(AT)usa.net), Jan 21 2008`

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Last modified October 12 15:26 EDT 2008. Contains 144830 sequences.

AT&T Labs Research