cp's OEIS Frontend

A361588 Triangle read by rows: T(n,k) is the number of digraphs on n unlabeled nodes with k strongly connected components and without isolated nodes.

%I A361588 #5 Mar 16 2023 19:46:17
%S A361588 1,0,0,0,1,1,0,5,4,4,0,83,57,37,25,0,5048,2411,1110,550,271,0,1047008,
%T A361588 325015,101467,37140,15024,5682,0,705422362,136887749,27765860,
%U A361588 7139149,2259378,780314,237684,0,1580348371788,183852357683,23088181536,3923330808,907186816,258971872,78716548,20042357
%N A361588 Triangle read by rows: T(n,k) is the number of digraphs on n unlabeled nodes with k strongly connected components and without isolated nodes.
%F A361588 T(n,k) = A361582(n,k) - A361582(n-1,k-1).
%e A361588 Triangle begins:
%e A361588   1;
%e A361588   0,       0;
%e A361588   0,       1,      1;
%e A361588   0,       5,      4,      4;
%e A361588   0,      83,     57,     37,    25;
%e A361588   0,    5048,   2411,   1110,   550,   271;
%e A361588   0, 1047008, 325015, 101467, 37140, 15024, 5682;
%e A361588   ...
%o A361588 (PARI) \\ See PARI link in A350794 for program code.
%o A361588 { my(A=A361588triang(6)); for(n=1, #A, print(A[n])) }
%Y A361588 Column k=1 is A035512.
%Y A361588 Main diagonal is A361589.
%Y A361588 Row sums are A053598.
%Y A361588 Cf. A350794, A361582, A361587, A361590.
%K A361588 nonn,tabl
%O A361588 0,8
%A A361588 _Andrew Howroyd_, Mar 16 2023