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%I #15 Aug 02 2021 02:29:02
%S 1,2,13,197,9312,1528634,880277970
%N Number of quasi-initially connected digraphs on n unlabeled nodes.
%C From _Sean A. Irvine_, Aug 01 2021: (Start)
%C A quasi-initially connected digraph is a digraph containing at least one vertex v such that every vertex u in the graph can either be reached from v or v can be reached from u (while obeying the directions on the edges).
%C There is no known formula. (End)
%H Sean A. Irvine, <a href="https://github.com/archmageirvine/joeis/blob/master/src/irvine/oeis/a049/A049512.java">Java program</a> (github)
%H V. Jovovic and G. Kilibarda, <a href="http://dx.doi.org/10.1016/S0012-365X(00)00112-6">Enumeration of labeled quasi-initially connected digraphs</a>, Discrete Math., 224 (2000), 151-163.
%Y Cf. A049414, A003085, A035512, A003088, A051421.
%K hard,more,nonn
%O 1,2
%A _Vladeta Jovovic_, Goran Kilibarda
%E a(6)-a(7) from _Sean A. Irvine_, Aug 01 2021
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