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%I #12 Aug 26 2022 18:50:23
%S 1,4,25,278,5532,200589,11662671,981458725,111213730857,
%T 16212510876591,2947663429595884,653299790376494253,
%U 173373367472722467460,54295204354760461199529,19822683467350158062736540
%N 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.
%C Cover may include multiple occurrences of a subset. Also n-rowed binary matrices with distinct rows and all row sums 4.
%H Vladeta Jovovic, <a href="/A058790/a058790.pdf">Formula</a>
%Y Row n=4 of A331508.
%Y Cf. A050535, A050913, A058783, A058784, A058785.
%K more,nonn
%O 1,2
%A _Vladeta Jovovic_, Nov 30 2000
%E a(8)-a(12) from _Andrew Howroyd_, Jan 29 2020
%E a(13)-a(15) from _Sean A. Irvine_, Aug 26 2022
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