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Search: id:A091070
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| A091070 |
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Number of automorphism groups of partial orders on n points. |
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+0
2
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| 1, 1, 2, 3, 6, 8, 16, 21, 41, 57, 103, 140, 276
(list; graph; listen)
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OFFSET
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0,3
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LINKS
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G. Pfeiffer, Subgroups.
G. Pfeiffer, Counting Transitive Relations, Journal of Integer Sequences, Vol. 7 (2004), Article 04.3.2.
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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).
Sequence in context: A129374 A048809 A047001 this_sequence A133586 A141348 A029867
Adjacent sequences: A091067 A091068 A091069 this_sequence A091071 A091072 A091073
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KEYWORD
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hard,nonn
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AUTHOR
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Goetz Pfeiffer (goetz.pfeiffer(AT)nuigalway.ie), Jan 21 2004
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