A058791 - OEIS

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A058791

Number of covers of an unlabeled n-set such that every point of the set is covered by exactly 4 subsets of the cover and that intersection of every 4 subsets of the cover contains at most one point.

1, 4, 25, 278, 5532, 200589, 11662671 (list; graph; refs; listen; history; internal format)

	OFFSET	`1,2`
	COMMENTS	`Cover may include multiple occurrences of a subset. Also n-rowed binary matrices with distinct rows and all row sums 4.`
	LINKS	`Formula`
	CROSSREFS	`Cf. A050535, A050913, A058783-A058785.` `Sequence in context: A071896 A065740 A144281 * A093959 A086216 A167041` `Adjacent sequences: A058788 A058789 A058790 * A058792 A058793 A058794`
	KEYWORD	`more,nonn`
	AUTHOR	`Vladeta Jovovic (vladeta(AT)eunet.rs), Nov 30 2000`

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Last modified February 14 11:36 EST 2012. Contains 205623 sequences.