cp's OEIS Frontend

A126123 Triangle read by rows: T(n,k) = number of edge-rooted unlabeled graphs having n nodes and k edges, n > 0, 0 < k <= n*(n-1)/2.

%I A126123 #5 May 03 2018 03:54:22
%S A126123 0,1,1,1,1,1,2,4,4,2,1,1,2,6,12,16,16,12,6,2,1,1,2,7,18,40,68,96,108,
%T A126123 96,68,40,18,7,2,1,1,2,7,20,56,135,281,500,764,982,1068,982,764,500,
%U A126123 281,135,56,20,7,2,1,1,2,7,21,63,181,485,1159,2499,4788,8074,11967,15566
%N A126123 Triangle read by rows: T(n,k) = number of edge-rooted unlabeled graphs having n nodes and k edges, n > 0, 0 < k <= n*(n-1)/2.
%D A126123 F. Harary and E. M. Palmer, Graphical Enumeration, Academic Press, NY, 1973.
%e A126123 0;
%e A126123 1;
%e A126123 1,1,1;
%e A126123 1,2,4,4,2,1;
%e A126123 1,2,6,12,16,16,12,6,2,1;
%e A126123 1,2,7,18,40,68,96,108,96,68,40,18,7,2,1;
%Y A126123 Cf. A126122 (row sums).
%K A126123 nonn,tabf
%O A126123 1,7
%A A126123 _Vladeta Jovovic_, Mar 07 2007