cp's OEIS Frontend

A123546 Triangle read by rows: T(n,k) = number of unlabeled graphs on n nodes with degree >= 3 at each node (n >= 1, 0 <= k <= n(n-1)/2).

%I A123546 #4 Mar 30 2012 16:50:35
%S A123546 0,0,0,0,0,0,0,0,0,0,0,0,0,0,1,0,0,0,0,0,0,0,0,1,1,1,0,0,0,0,0,0,0,0,
%T A123546 0,2,4,5,4,2,1,1,0,0,0,0,0,0,0,0,0,0,0,4,18,30,34,29,17,9,5,2,1,1,0,0,
%U A123546 0,0,0,0,0,0,0,0,0,0,6,35,136,309,465,505,438,310,188,103,52,23
%N A123546 Triangle read by rows: T(n,k) = number of unlabeled graphs on n nodes with degree >= 3 at each node (n >= 1, 0 <= k <= n(n-1)/2).
%D A123546 R. W. Robinson, Numerical implementation of graph counting algorithms, AGRC Grant, Math. Dept., Univ. Newcastle, Australia, 1978.
%H A123546 R. W. Robinson, <a href="/A123546/b123546.txt">Rows 0 through 14, flattened</a>
%e A123546 Triangle begins:
%e A123546 n = 0
%e A123546 k = 0 : 0
%e A123546 ************************* total (n = 0) = 0
%e A123546 n = 1
%e A123546 k = 0 : 0
%e A123546 ************************* total (n = 1) = 0
%e A123546 n = 2
%e A123546 k = 0 : 0
%e A123546 k = 1 : 0
%e A123546 ************************* total (n = 2) = 0
%e A123546 n = 3
%e A123546 k = 0 : 0
%e A123546 k = 1 : 0
%e A123546 k = 2 : 0
%e A123546 k = 3 : 0
%e A123546 ************************* total (n = 3) = 0
%e A123546 n = 4
%e A123546 k = 0 : 0
%e A123546 k = 1 : 0
%e A123546 k = 2 : 0
%e A123546 k = 3 : 0
%e A123546 k = 4 : 0
%e A123546 k = 5 : 0
%e A123546 k = 6 : 1
%e A123546 ************************* total (n = 4) = 1
%e A123546 n = 5
%e A123546 k = 0 : 0
%e A123546 k = 1 : 0
%e A123546 k = 2 : 0
%e A123546 k = 3 : 0
%e A123546 k = 4 : 0
%e A123546 k = 5 : 0
%e A123546 k = 6 : 0
%e A123546 k = 7 : 0
%e A123546 k = 8 : 1
%e A123546 k = 9 : 1
%e A123546 k = 10 : 1
%e A123546 ************************* total (n = 5) = 3
%Y A123546 Row sums give A007111. Cf. A007112, A123545.
%K A123546 nonn,tabf
%O A123546 0,36
%A A123546 _N. J. A. Sloane_, Nov 14 2006