%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