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A361912
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The number of unlabeled graded posets with n elements.
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5
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1, 1, 2, 4, 10, 28, 93, 354, 1621, 9110, 64801, 595976, 7204091, 115561423, 2473540433, 70853213144, 2720354016419, 140170631441858, 9702605436760235, 903309202327818566, 113234129823368903523, 19137461395401601912043, 4366007821745938984134203
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OFFSET
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0,3
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COMMENTS
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A partially ordered set is graded if all maximal chains have the same length. This is called tiered by some authors.
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LINKS
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PROG
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(Sage) sum(1 for P in posets(n) if P.is_graded())
(PARI) \\ See PARI link in A361957 for program code.
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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