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A355755
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Irregular triangle read by rows: T(n,k) is the number of unlabeled connected n-node graphs with intersection number (or edge clique cover number) k; n >= 1, 0 <= k <= floor(n^2/4).
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2
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1, 0, 1, 0, 1, 1, 0, 1, 2, 2, 1, 0, 1, 4, 7, 6, 2, 1, 0, 1, 6, 22, 36, 27, 13, 4, 2, 1, 0, 1, 9, 53, 161, 242, 209, 111, 43, 17, 5, 1, 1, 0, 1, 12, 114, 611, 1766, 2903, 2793, 1723, 773, 284, 86, 36, 9, 3, 2, 1, 0, 1, 16, 221, 1987, 10517, 33078, 60639, 67379, 48035, 24628, 9715, 3349, 1049, 310, 105, 36, 9, 4, 1, 1
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OFFSET
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1,9
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LINKS
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FORMULA
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T(n,0) = 0 if n > 1.
T(n,1) = 1.
T(n,2) = floor((n-1)^2/4) = A002620(n-1).
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EXAMPLE
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Triangle begins:
n\k | 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16
----+--------------------------------------------------------------
1 | 1
2 | 0 1
3 | 0 1 1
4 | 0 1 2 2 1
5 | 0 1 4 7 6 2 1
6 | 0 1 6 22 36 27 13 4 2 1
7 | 0 1 9 53 161 242 209 111 43 17 5 1 1
8 | 0 1 12 114 611 1766 2903 2793 1723 773 284 86 36 9 3 2 1
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CROSSREFS
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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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