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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. 1

%I #5 May 03 2018 03:54:22

%S 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 96,68,40,18,7,2,1,1,2,7,20,56,135,281,500,764,982,1068,982,764,500,

%U 281,135,56,20,7,2,1,1,2,7,21,63,181,485,1159,2499,4788,8074,11967,15566

%N 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 F. Harary and E. M. Palmer, Graphical Enumeration, Academic Press, NY, 1973.

%e 0;

%e 1;

%e 1,1,1;

%e 1,2,4,4,2,1;

%e 1,2,6,12,16,16,12,6,2,1;

%e 1,2,7,18,40,68,96,108,96,68,40,18,7,2,1;

%Y Cf. A126122 (row sums).

%K nonn,tabf

%O 1,7

%A _Vladeta Jovovic_, Mar 07 2007

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Last modified June 7 11:23 EDT 2024. Contains 373172 sequences. (Running on oeis4.)