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Search: id:A037184
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| A037184 |
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Functional digraphs with 1 node not in the image. |
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+0
1
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| 6, 48, 420, 3840, 38010, 407904, 4739112, 59405760, 800309070, 11542072080, 177536452236, 2902434644928, 50271450894210, 919799178083520, 17730187503894480, 359183503307677824, 7629999730919490582
(list; graph; listen)
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OFFSET
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3,1
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COMMENT
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Comment from Christian Bower: Labeled graphs where every node has outdegree 1, one node has indegree 0, one node has indegree 2, all other nodes have indegree 1 and there are no loops of length 1.
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FORMULA
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a(n) = n [ (n-2) a(n-1) +(n-1) a(n-2) ] / (n-3); g.f. = x^3/((1-x)^3 e^x)
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CROSSREFS
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A000166 (derangements) gives number of functional digraphs with all nodes in the range, A007778 gives number of functional digraphs with n nodes.
Sequence in context: A083233 A002918 A005399 this_sequence A085457 A105627 A051578
Adjacent sequences: A037181 A037182 A037183 this_sequence A037185 A037186 A037187
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KEYWORD
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easy,nonn
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AUTHOR
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Erich Friedman (erich.friedman(AT)stetson.edu)
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