|
|
A026586
|
|
Number of labeled essential directed acyclic graphs (DAGs).
|
|
0
|
|
|
1, 1, 1, 4, 59, 2616, 306117, 87716644, 58874478231, 90018247082416, 307775459402071913, 2322338398654088751036, 38293189001166839643861795, 1369158635491114830895696234696, 105480725505896171175318367295035341
(list;
graph;
refs;
listen;
history;
text;
internal format)
|
|
|
OFFSET
|
0,4
|
|
LINKS
|
|
|
FORMULA
|
a(0)=1, a(n) = Sum_{k=1..n} (-1)^(k+1) * binomial(n, k) * (2^(n-k)-n+k) * a(n-k) [from Steinsky]. - Sean A. Irvine, Oct 06 2019
|
|
CROSSREFS
|
|
|
KEYWORD
|
nonn
|
|
AUTHOR
|
Detlef Pauly (dettodet(AT)yahoo.de), Aug 22 2003
|
|
EXTENSIONS
|
|
|
STATUS
|
approved
|
|
|
|