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A350797
Triangle read by rows: T(n,k) is the number of digraphs on n unlabeled nodes with k arcs and a global source (or sink), n >= 1, k = 0..(n-1)^2.
6
1, 0, 1, 0, 0, 2, 2, 1, 0, 0, 0, 4, 11, 19, 15, 8, 2, 1, 0, 0, 0, 0, 9, 45, 157, 319, 453, 455, 352, 199, 93, 32, 9, 2, 1, 0, 0, 0, 0, 0, 20, 167, 928, 3395, 9015, 18172, 29089, 37688, 40446, 36267, 27476, 17560, 9543, 4354, 1688, 547, 157, 36, 9, 2, 1
OFFSET
1,6
LINKS
Andrew Howroyd, Table of n, a(n) for n = 1..2490 (rows 1..20)
EXAMPLE
Triangle begins:
[1] 1;
[2] 0, 1;
[3] 0, 0, 2, 2, 1;
[4] 0, 0, 0, 4, 11, 19, 15, 8, 2, 1;
...
PROG
(PARI) \\ See PARI link in A350794 for program code.
{ my(A=A350797triang(5)); for(n=1, #A, print(A[n])) }
CROSSREFS
Row sums are A350360.
Column sums are A350798.
The leading diagonal is A000081.
The labeled version is A350793.
Sequence in context: A049783 A287320 A210502 * A283988 A276204 A365573
KEYWORD
nonn,tabf
AUTHOR
Andrew Howroyd, Jan 21 2022
STATUS
approved