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A354693
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Number of unlabeled prime posets with n elements.
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0
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1, 0, 0, 1, 4, 28, 234, 2585, 36326, 646405, 14528011, 412212506
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OFFSET
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1,5
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COMMENTS
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A poset P is called prime if it is not decomposable. A poset Q is called decomposable if Q can be obtained as the composition (lexicographic product) of the outer poset Q' and the inner posets Qi, 1 <= i <= r, where |Q'| = r > 1 and at least one of the posets Qi is nonsingleton.
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CROSSREFS
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KEYWORD
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nonn,more
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AUTHOR
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STATUS
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approved
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