[seqfan] weakly connected unlabeled digraphs, indegrees and outdegrees >0

Richard J. Mathar mathar at mpia-hd.mpg.de
Mon Nov 6 20:51:33 CET 2023

This comes into mind while reading https://math.stackexchange.com/questions/4801609/ :

In how far is A121933 a complement to A002031?
Is n in A002031 the number of arcs or the number of nodes?
Does the unlabeled version of A121933 exist in the OEIS?
(Does A121933 count connected graphs? Does it allow multi-arcs and/or loops?
Apparently A086193 is the version without loops, and A121252 the weakly connected
but not restricting degrees...


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