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A123534
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Triangular array T(n,k) giving number of 2-connected graphs with n labeled nodes and k edges (n >= 3, n <= k <= n(n-1)/2).
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3
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1, 3, 6, 1, 12, 70, 100, 45, 10, 1, 60, 720, 2445, 3535, 2697, 1335, 455, 105, 15, 1, 360, 7560, 46830, 133581, 216951, 232820, 183540, 111765, 53627, 20307, 5985, 1330, 210, 21, 1, 2520, 84000, 835800, 3940440, 10908688, 20317528
(list; graph; refs; listen; history; internal format)
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OFFSET
| 3,2
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REFERENCES
| R. W. Robinson, Numerical implementation of graph counting algorithms, AGRC Grant, Math. Dept., Univ. Newcastle, Australia, 1977.
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LINKS
| R. W. Robinson, Rows 3 through 15, flattened (row 15 is incomplete).
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EXAMPLE
| Triangle begins:
n = 3
k = 3 : 1
****** total( 3) = 1
n = 4
k = 4 : 3
k = 5 : 6
k = 6 : 1
****** total( 4) = 10
n = 5
k = 5 : 12
k = 6 : 70
k = 7 : 100
k = 8 : 45
k = 9 : 10
k = 10 : 1
****** total( 5) = 238
n = 6
k = 6 : 60
k = 7 : 720
k = 8 : 2445
k = 9 : 3535
k = 10 : 2697
k = 11 : 1335
k = 12 : 455
k = 13 : 105
k = 14 : 15
k = 15 : 1
****** total( 6) = 11368
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CROSSREFS
| Row sums give A013922. Cf. A062734, A123527.
Sequence in context: A130724 A120229 A192100 * A100960 A130852 A138799
Adjacent sequences: A123531 A123532 A123533 * A123535 A123536 A123537
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KEYWORD
| nonn,tabf
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AUTHOR
| N. J. A. Sloane (njas(AT)research.att.com), Nov 13 2006
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