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A136605
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Triangle read by rows: T(n,k) = number of forests on n unlabeled nodes with k edges (n>=1, 0<=k<=n-1).
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2
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1, 1, 1, 1, 1, 1, 1, 1, 2, 2, 1, 1, 2, 3, 3, 1, 1, 2, 4, 6, 6, 1, 1, 2, 4, 7, 11, 11, 1, 1, 2, 4, 8, 14, 23, 23, 1, 1, 2, 4, 8, 15, 29, 46, 47, 1, 1, 2, 4, 8, 16, 32, 60, 99, 106, 1, 1, 2, 4, 8, 16, 33, 66, 128, 216, 235, 1, 1, 2, 4, 8, 16, 34, 69, 143, 284, 488, 551, 1, 1, 2, 4
(list; table; graph; refs; listen; history; internal format)
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OFFSET
| 1,9
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REFERENCES
| F. Harary and E. M. Palmer, Graphical Enumeration, Academic Press, NY, 1973, pp. 58-59.
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EXAMPLE
| Triangle begins:
1
1,1
1,1,1
1,1,2,2
1,1,2,3,3
1,1,2,4,6,6 <- T(6,3) = 4 forests on 6 nodes with 3 edges.
1,1,2,4,7,11,11
1,1,2,4,8,14,23,23
1,1,2,4,8,15,29,46,47
1,1,2,4,8,16,32,60,99,106
1,1,2,4,8,16,33,66,128,216,235
1,1,2,4,8,16,34,69,143,284,488,551
1,1,2,4,8,16,34,70,149,315,636,1121,1301
1,1,2,4,8,16,34,71,152,330,710,1467,2644,3159
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CROSSREFS
| Row sums give A005195. Rightmost diagonal gives A000055. Cf. A001858, A138464.
Sequence in context: A161638 A066030 A025863 * A165621 A004739 A156282
Adjacent sequences: A136602 A136603 A136604 * A136606 A136607 A136608
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KEYWORD
| nonn,tabl
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AUTHOR
| N. J. A. Sloane (njas(AT)research.att.com), May 09 2008
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