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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.

%I A350797 #9 Jan 22 2022 23:43:20
%S A350797 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,
%T A350797 352,199,93,32,9,2,1,0,0,0,0,0,20,167,928,3395,9015,18172,29089,37688,
%U A350797 40446,36267,27476,17560,9543,4354,1688,547,157,36,9,2,1
%N 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.
%H A350797 Andrew Howroyd, <a href="/A350797/b350797.txt">Table of n, a(n) for n = 1..2490</a> (rows 1..20)
%e A350797 Triangle begins:
%e A350797   [1] 1;
%e A350797   [2] 0, 1;
%e A350797   [3] 0, 0, 2, 2,  1;
%e A350797   [4] 0, 0, 0, 4, 11, 19, 15, 8, 2, 1;
%e A350797   ...
%o A350797 (PARI) \\ See PARI link in A350794 for program code.
%o A350797 { my(A=A350797triang(5)); for(n=1, #A, print(A[n])) }
%Y A350797 Row sums are A350360.
%Y A350797 Column sums are A350798.
%Y A350797 The leading diagonal is A000081.
%Y A350797 The labeled version is A350793.
%Y A350797 Cf. A057277, A057278, A350795.
%K A350797 nonn,tabf
%O A350797 1,6
%A A350797 _Andrew Howroyd_, Jan 21 2022