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%I #15 May 30 2022 18:03:18
%S 1,0,1,1,0,0,3,4,4,1,1,0,0,0,7,21,37,47,38,27,13,5,1,1,0,0,0,0,18,90,
%T 309,661,1125,1477,1665,1489,1154,707,379,154,61,16,5,1,1,0,0,0,0,0,
%U 44,374,1981,7107,19166,41867,77194,122918,170308,206980,220768,207301,171008,124110,78813,43862,21209,8951,3242,1043,288,76,17,5,1,1
%N Triangle T(n,k) of number of digraphs with a quasi-source on n unlabeled nodes and with k arcs, k = 0..n*(n-1).
%H Sean A. Irvine, <a href="https://github.com/archmageirvine/joeis/blob/master/src/irvine/oeis/a234/A234007.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.
%e Table starts:
%e [1],
%e [0,1,1],
%e [0,0,3,4,4,1,1],
%e [0,0,0,7,21,37,47,38,27,13,5,1,1],
%e ...
%e Number of digraphs with a quasi-source on 3 unlabeled nodes is 13=3+4+4+1+1.
%Y Row sums give A049512. Cf. A057270-A057278.
%K nonn,tabf
%O 1,7
%A _Vladeta Jovovic_, Goran Kilibarda, Sep 14 2000
%E More terms from _Sean A. Irvine_, May 30 2022