cp's OEIS Frontend

A049524 Number of digraphs with a source and a sink on n labeled nodes.

%I A049524 #21 Jan 16 2022 17:46:25
%S A049524 1,3,48,3424,962020,1037312116,4344821892264,71771421308713624,
%T A049524 4716467927380427847264,1237465168798883061207535456,
%U A049524 1297923989772809185944542332007104,5444330658513426322624322033259452670016,91342931436147421630261703458729460990513248512
%N A049524 Number of digraphs with a source and a sink on n labeled nodes.
%C A049524 Here a source is defined to be a node which has a directed path to all other nodes and a sink to be a node to which all other nodes have a directed path. A digraph with a source and a sink can also be described as initially-finally connected. - _Andrew Howroyd_, Jan 16 2022
%D A049524 V. Jovovic, G. Kilibarda, Enumeration of labeled initially-finally connected digraphs, Scientific review, Serbian Scientific Society, 19-20 (1996), p. 244.
%H A049524 Andrew Howroyd, <a href="/A049524/b049524.txt">Table of n, a(n) for n = 1..50</a>
%H A049524 Sean A. Irvine, <a href="https://github.com/archmageirvine/joeis/blob/master/src/irvine/oeis/a049/A049524.java">Java program</a> (github)
%H A049524 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.
%H A049524 R. W. Robinson, <a href="http://cobweb.cs.uga.edu/~rwr/publications/components.pdf">Counting digraphs with restrictions on the strong components</a>, Combinatorics and Graph Theory '95 (T.-H. Ku, ed.), World Scientific, Singapore (1995), 343-354.
%o A049524 (PARI) InitFinally(15) \\ See A057271. - _Andrew Howroyd_, Jan 16 2022
%Y A049524 The unlabeled version is A049531.
%Y A049524 Row sums of A057271.
%Y A049524 Cf. A003027, A003028, A003029, A003030, A049414, A350790.
%K A049524 nonn
%O A049524 1,2
%A A049524 _Vladeta Jovovic_, Goran Kilibarda
%E A049524 Terms a(12) and beyond from _Andrew Howroyd_, Jan 16 2022