VOOZH about

URL: https://oeis.org/A350789

⇱ A350789 - OEIS

login
A350789
Triangle read by rows: T(n,k) is the number of unlabeled weakly connected digraphs with n arcs and k vertices, k = 1..n+1.
5
1, 0, 1, 0, 1, 3, 0, 0, 4, 8, 0, 0, 4, 22, 27, 0, 0, 1, 37, 108, 91, 0, 0, 1, 47, 326, 582, 350, 0, 0, 0, 38, 667, 2432, 3024, 1376, 0, 0, 0, 27, 1127, 7694, 17314, 16008, 5743, 0, 0, 0, 13, 1477, 19646, 74676, 117312, 84494, 24635
OFFSET
0,6
LINKS
Andrew Howroyd, Table of n, a(n) for n = 0..1325 (rows 0..50)
EXAMPLE
Triangle begins:
1;
0, 1;
0, 1, 3;
0, 0, 4, 8;
0, 0, 4, 22, 27;
0, 0, 1, 37, 108, 91;
0, 0, 1, 47, 326, 582, 350;
0, 0, 0, 38, 667, 2432, 3024, 1376;
0, 0, 0, 27, 1127, 7694, 17314, 16008, 5743;
...
PROG
(PARI) \\ See A054733 for G, InvEulerMTS
T(n)={my(p=InvEulerMTS(sum(i=0, n, G(i, y+O(y^n))*x^i, O(x*x^n)))); vector(n, n, Vec(O(x^n)+polcoef(p, n-1, y)/x, -n))}
{ my(A=T(10)); for(n=1, #A, print(A[n])) }
CROSSREFS
Row sums are A053454.
Column sums are A003085.
Main diagonal is A000238.
Cf. A054733 (transpose), A350450 (acyclic), A350753 (strongly connected).
Sequence in context: A305223 A316801 A143044 * A361357 A305151 A127775
KEYWORD
nonn,tabl
AUTHOR
Andrew Howroyd, Jan 28 2022
STATUS
approved