A058793 Number of covers of an unlabeled n-set such that every point of the set is covered by exactly 6 subsets of the cover and that intersection of every 6 subsets of the cover contains at most one point.

1, 6, 73, 2957, 431805, 193413963, 198914729182, 389238347659505, 1292594846197639190, 6753309741099683530616

Offset: 1

Author

Vladeta Jovovic, Nov 30 2000

Keywords

• more
• nonn

Comments

Cover may include multiple occurrences of a subset. Also n-rowed binary matrices with distinct rows and all row sums 6.

Links

• Vladeta Jovovic, Formula

Crossrefs

Row n=6 of A331508.

Cf. A050535, A050913, A058783, A058784, A058785.

Extensions

a(6)-a(10) from Andrew Howroyd, Jan 29 2020