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A361957
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Triangle read by rows: T(n,k) is the number of unlabeled tiered posets with n elements and height k.
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5
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1, 0, 1, 0, 1, 1, 0, 1, 2, 1, 0, 1, 5, 3, 1, 0, 1, 12, 10, 4, 1, 0, 1, 35, 35, 16, 5, 1, 0, 1, 108, 149, 66, 23, 6, 1, 0, 1, 393, 755, 327, 106, 31, 7, 1, 0, 1, 1666, 4736, 1936, 566, 156, 40, 8, 1, 0, 1, 8543, 37394, 14130, 3578, 878, 217, 50, 9, 1
(list;
table;
graph;
refs;
listen;
history;
text;
internal format)
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OFFSET
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0,9
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COMMENTS
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A tiered poset is a partially ordered set in which every maximal chain has the same length.
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LINKS
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EXAMPLE
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Triangle begins:
1;
0, 1;
0, 1, 1;
0, 1, 2, 1;
0, 1, 5, 3, 1;
0, 1, 12, 10, 4, 1;
0, 1, 35, 35, 16, 5, 1;
0, 1, 108, 149, 66, 23, 6, 1;
0, 1, 393, 755, 327, 106, 31, 7, 1;
0, 1, 1666, 4736, 1936, 566, 156, 40, 8, 1;
...
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PROG
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(PARI) \\ See link for program code.
{ my(A=A361957tabl(9)); for(i=1, #A, print(A[i, 1..i])) }
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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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