id:A000226 - OEIS Search Results

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Number of n-node unlabeled connected graphs with one cycle of length 3.
(Formerly M2668 N1066)

+0
6

1, 1, 3, 7, 18, 44, 117, 299, 793, 2095, 5607, 15047, 40708, 110499, 301541, 825784, 2270211, 6260800, 17319689, 48042494, 133606943, 372430476, 1040426154, 2912415527, 8167992598, 22947778342, 64577555147 (list; graph; listen)

	OFFSET	`3,3`
	COMMENT	`Number of rooted trees where root has degree 3. - Christian Bower (bowerc(AT)usa.net)`
	REFERENCES	`J. Riordan, An Introduction to Combinatorial Analysis, Wiley, 1958, p. 150.`
	LINKS	`Index entries for sequences related to rooted trees`
	FORMULA	`G.f.: (r(x)^3+3r(x)r(x^2)+2*r(x^3))/6 where r(x) is g. f. for rooted trees (A000081).`
	CROSSREFS	`Adjacent sequences: A000223 A000224 A000225 this_sequence A000227 A000228 A000229` `Sequence in context: A129921 A036670 A027967 this_sequence A036883 A114713 A116413`
	KEYWORD	`nonn,nice`
	AUTHOR	`njas`
	EXTENSIONS	`More terms from Vladeta Jovovic (vladeta(AT)Eunet.yu), Apr 19 2000`

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Last modified May 15 13:16 EDT 2008. Contains 139641 sequences.

AT&T Labs Research