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A263859
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Triangle read by rows: T(n,k) (n>=1, k>=0) is the number of posets with n elements and rank k (or depth k+1).
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6
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1, 1, 1, 1, 3, 1, 1, 8, 6, 1, 1, 20, 31, 10, 1, 1, 55, 162, 84, 15, 1, 1, 163, 940, 734, 185, 21, 1, 1, 556, 6372, 7305, 2380, 356, 28, 1, 1, 2222, 52336, 86683, 35070, 6259, 623, 36, 1, 1, 10765, 534741, 1261371, 619489, 125597, 14258, 1016, 45, 1
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refs;
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history;
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OFFSET
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1,5
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COMMENTS
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The rank of a poset is the number of cover relations in a maximal chain.
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LINKS
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Peter Steinbach, Field Guide to Simple Graphs, Volume 4, Part 10 (For Volumes 1, 2, 3, 4 of this book see A000088, A008406, A000055, A000664, respectively.)
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EXAMPLE
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Triangle begins:
1,
1,1,
1,3,1,
1,8,6,1,
1,20,31,10,1,
1,55,162,84,15,1,
1,163,940,734,185,21,1,
1,556,6372,7305,2380,356,28,1,
1,2222,52336,86683,35070,6259,623,36,1,
1,10765,534741,1261371,619489,125597,14258,1016,45,1,
...
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CROSSREFS
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KEYWORD
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AUTHOR
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EXTENSIONS
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More terms from Brinkmann-McKay (2002) added by N. J. A. Sloane, Mar 18 2017
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STATUS
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approved
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