id:A065889 - OEIS Search Results

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a(n) = number of unicyclic connected simple graphs whose cycle has length 4.

+0
3

3, 60, 1080, 20580, 430080, 9920232, 252000000, 7015381560, 212840939520, 6998969586180, 248180493969408, 9445533398437500, 384213343210045440, 16639691095281974160, 764619269867445288960, 37163398969133506235952 (list; graph; listen)

	OFFSET	`4,1`
	FORMULA	`E.g.f.: T^4/8, where T = T(x) is Euler's tree function (see A000169)` `a(n) = (n-1)(n-2)(n-3)*n^(n-4)/2. - Vladeta Jovovic (vladeta(AT)Eunet.yu), Oct 26 2004`
	CROSSREFS	`A065888 ( = 2*A065889) counts sagittal graphs with one cycle (length 4)` `A column of A098909, A053507.` `Sequence in context: A002738 A006432 A115490 this_sequence A001084 A137150 A081854` `Adjacent sequences: A065886 A065887 A065888 this_sequence A065890 A065891 A065892`
	KEYWORD	`nonn`
	AUTHOR	`Len Smiley (smiley(AT)math.uaa.alaska.edu), Nov 27 2001`

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Last modified August 29 17:54 EDT 2008. Contains 143238 sequences.

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