

A058791


Number of covers of an unlabeled nset 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



1, 4, 25, 278, 5532, 200589, 11662671, 981458725, 111213730857, 16212510876591, 2947663429595884, 653299790376494253
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OFFSET

1,2


COMMENTS

Cover may include multiple occurrences of a subset. Also nrowed binary matrices with distinct rows and all row sums 4.


LINKS

Table of n, a(n) for n=1..12.
Vladeta Jovovic, Formula


CROSSREFS

Row n=4 of A331508.
Cf. A050535, A050913, A058783, A058784, A058785.
Sequence in context: A308008 A144281 A320569 * A216660 A238510 A222982
Adjacent sequences: A058788 A058789 A058790 * A058792 A058793 A058794


KEYWORD

more,nonn


AUTHOR

Vladeta Jovovic, Nov 30 2000


EXTENSIONS

a(8)a(12) from Andrew Howroyd, Jan 29 2020


STATUS

approved



