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A350772
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Triangle read by rows: T(n,k) is the number of n-element unlabeled series-parallel posets with k connected components.
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0
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1, 1, 1, 3, 1, 1, 9, 4, 1, 1, 30, 12, 4, 1, 1, 103, 45, 13, 4, 1, 1, 375, 160, 48, 13, 4, 1, 1, 1400, 613, 175, 49, 13, 4, 1, 1, 5380, 2354, 680, 178, 49, 13, 4, 1, 1
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OFFSET
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1,4
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LINKS
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EXAMPLE
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Triangle begins:
1;
1, 1;
3, 1, 1;
9, 4, 1, 1;
30, 12, 4, 1, 1;
103, 45, 13, 4, 1, 1;
375, 160, 48, 13, 4, 1, 1;
1400, 613, 175, 49, 13, 4, 1, 1;
5380, 2354, 680, 178, 49, 13, 4, 1, 1;
...
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CROSSREFS
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KEYWORD
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AUTHOR
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STATUS
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approved
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