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A360870
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Triangle read by rows: T(n,k) is the number of unlabeled connected multigraphs with n edges on k nodes, no cut-points and degree >= 3 at each node, loops allowed, n >= 2, 1 <= k <= floor(2*n/3).
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4
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1, 1, 2, 1, 4, 1, 7, 2, 1, 10, 8, 2, 1, 14, 19, 11, 1, 18, 40, 48, 7, 1, 23, 77, 154, 70, 5, 1, 28, 132, 421, 392, 71, 1, 34, 217, 1008, 1638, 690, 35, 1, 40, 340, 2210, 5623, 4548, 767, 16, 1, 47, 510, 4477, 16745, 22657, 8594, 566, 1, 54, 742, 8557, 44698, 92844, 64716, 11247, 226
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OFFSET
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2,3
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COMMENTS
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Columns k >= 3 correspond to the 2-connected graphs.
Terms may be computed using the tools geng, vcolg and multig in nauty with some additional processing to check the degrees of nodes.
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LINKS
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EXAMPLE
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Triangle begins:
1;
1, 2;
1, 4;
1, 7, 2;
1, 10, 8, 2;
1, 14, 19, 11;
1, 18, 40, 48, 7;
1, 23, 77, 154, 70, 5;
1, 28, 132, 421, 392, 71;
1, 34, 217, 1008, 1638, 690, 35;
1, 40, 340, 2210, 5623, 4548, 767, 16;
1, 47, 510, 4477, 16745, 22657, 8594, 566;
1, 54, 742, 8557, 44698, 92844, 64716, 11247, 226;
...
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CROSSREFS
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Row sums except first column are A360871.
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KEYWORD
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nonn,tabf
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AUTHOR
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STATUS
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approved
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