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A354693
Number of unlabeled prime posets with n elements.
0
1, 0, 0, 1, 4, 28, 234, 2585, 36326, 646405, 14528011, 412212506
OFFSET
1,5
COMMENTS
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.
LINKS
S. M. Khamis, On numerical counting of prime, UPO, and the general type of posets according to heights, Congressus Numerantium, 146 (2000), 157-171.
S. M. Khamis, Recognition of prime posets and one of its applications, J. Egypt. Math. Soc., 14 (1) (2006), 5-13.
CROSSREFS
KEYWORD
nonn,more
AUTHOR
STATUS
approved