OFFSET
1,2
COMMENTS
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 01 2022
REFERENCES
V. Jovovic, G. Kilibarda, Enumeration of labeled initially-finally connected digraphs, Scientific review, Serbian Scientific Society, 19-20 (1996), p. 246.
LINKS
Andrew Howroyd, Table of n, a(n) for n = 1..50
PROG
(PARI) \\ See PARI link in A350794 for program code.
A049531seq(15) \\ Andrew Howroyd, Jan 21 2022
CROSSREFS
KEYWORD
nonn,nice
AUTHOR
Vladeta Jovovic, Goran Kilibarda
EXTENSIONS
a(6)-a(7) from Andrew Howroyd, Jan 01 2022
Terms a(8) and beyond from Andrew Howroyd, Jan 20 2022
STATUS
approved