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Search: id:A125702
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| A125702 |
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Number of connected categories with n objects and 2n-1 morphisms. |
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+0
3
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| 1, 1, 2, 3, 6, 10, 22, 42, 94, 203, 470, 1082, 2602, 6270, 15482, 38525, 97258, 247448, 635910, 1645411, 4289010, 11245670, 29656148, 78595028, 209273780, 559574414, 1502130920, 4046853091, 10939133170, 29661655793
(list; graph; listen)
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OFFSET
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1,3
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COMMENT
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Also number of connected antitransitive relations on n objects (antitransitive meaning a R b and b R c implies not a R c); equivalently, number of free oriented bipartite trees, with all arrows going from one part to the other part.
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CROSSREFS
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Same as A122086 except for n = 1; see there for formulas. Cf. A125699.
Sequence in context: A049527 A074371 A032202 this_sequence A052817 A156803 A002992
Adjacent sequences: A125699 A125700 A125701 this_sequence A125703 A125704 A125705
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KEYWORD
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nonn
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AUTHOR
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Franklin T. Adams-Watters (FrankTAW(AT)Netscape.net) and Christian Bower (bowerc(AT)usa.net), Jan 05 2007
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