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A091070
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Number of automorphism groups of partial orders on n points.
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1
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1, 1, 2, 3, 6, 8, 16, 21, 41, 57, 103, 140, 276
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OFFSET
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0,3
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LINKS
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EXAMPLE
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a(3)=3 because of the 5 partial orders on 3 points, 2 have trivial automorphism group, 2 have an automorphism of order 2 and one has the full symmetric group as its automorphism group; thus 3 different (conjugacy classes of) subgroups occur.
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CROSSREFS
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Cf. A000638 (subgroups of the symmetric group), A000112 (partial orders).
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KEYWORD
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hard,more,nonn
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AUTHOR
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Goetz Pfeiffer (goetz.pfeiffer(AT)nuigalway.ie), Jan 21 2004
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STATUS
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approved
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