Year-end appeal: Please make a donation to the OEIS Foundation to support ongoing development and maintenance of the OEIS. We are now in our 61st year, we have over 378,000 sequences, and we’ve reached 11,000 citations (which often say “discovered thanks to the OEIS”).
%I M3156 #23 Jan 19 2022 17:25:25
%S 1,3,48,3400,955860,1034141596,4340689156440,71756043154026904,
%T 4716284688998245793376,1237457313794197125403483936,
%U 1297922676419612772784598299454784,5444329780242560941321703550018388707904,91342929096228825123968637168641318872709897472
%N Number of unilaterally connected digraphs with n labeled nodes.
%D V. Jovovic, G. Kilibarda, Enumeration of labeled initially-finally connected digraphs, Scientific review, Serbian Scientific Society, 19-20 (1996), 237-247.
%D R. W. Robinson, Counting labeled acyclic digraphs, pp. 239-273 of F. Harary, editor, New Directions in the Theory of Graphs. Academic Press, NY, 1973.
%D N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).
%H Andrew Howroyd, <a href="/A003029/b003029.txt">Table of n, a(n) for n = 1..50</a>
%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.
%o (PARI) Unilaterally(12) \\ See A057275. - _Andrew Howroyd_, Jan 19 2022
%Y The unlabeled version is A003088.
%Y Row sums of A057275.
%Y Cf. A003027, A003028, A003030, A049524, A049414.
%K nonn,nice,easy
%O 1,2
%A _N. J. A. Sloane_
%E Corrected and extended by _Vladeta Jovovic_, Goran Kilibarda
%E Terms a(12) and beyond from _Andrew Howroyd_, Jan 11 2022