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%I #28 Feb 20 2023 22:08:38
%S 1,2,12,185,8990,1505939,875542491,1789247738400,13018820342147705,
%T 341188114831706152794,32520852428719860881939391,
%U 11366533535523591133597276823755,14669006027884671703581740693080811331,70315546525961698601351615055416574931833334
%N Number of digraphs on n unlabeled nodes with a sink (or, with a source).
%C Here a sink is defined to be a node to which all other nodes have a directed path. - _Andrew Howroyd_, Dec 27 2021
%D F. Harary and E. M. Palmer, Graphical Enumeration, Academic Press, NY, 1973, p. 218 (incorrect version).
%D Ronald C. Read, email to _N. J. A. Sloane_, 28 August, 2000.
%H Andrew Howroyd, <a href="/A051421/b051421.txt">Table of n, a(n) for n = 1..50</a>
%o (PARI) \\ See PARI link in A350794 for program code.
%o A051421seq(15) \\ _Andrew Howroyd_, Jan 21 2022
%Y The labeled case is A003028.
%Y Row sums of A057277.
%Y Cf. A003085, A035512, A003088, A049531, A350415, A350360, A350794.
%K nonn,nice
%O 1,2
%A _Vladeta Jovovic_
%E a(6) corrected and a(7) from _Sean A. Irvine_, Sep 11 2021
%E a(0)=1 removed and terms a(8) and beyond from _Andrew Howroyd_, Jan 21 2022
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