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Search: id:A098721
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| A098721 |
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a(n) = C(n, 2)^(n-3) = (n(n-1)/2)^(n-3). |
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+0
11
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| 1, 1, 6, 100, 3375, 194481, 17210368, 2176782336, 373669453125, 83733937890625, 23762680013799936, 8335775831236199424, 3543686674874777831491, 1795856326022129150390625, 1069932053790720000000000000
(list; graph; listen)
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OFFSET
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2,3
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COMMENT
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Comment from Saverio Caminiti and Emanuele G. Fusco (fusco(AT)di.uniroma1.it), Sep 18 2007: There is a flaw in the paper by Lamathe that we point out in our contribution. This sequence does not give the number of labeled 2-arch graphs (here named arch graphs) on n nodes. The correct sequence is given in our paper.
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REFERENCES
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B. Leclerc, Graphes d'arches, Math. Sci. Hum. 157 (2002), 27-48.
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LINKS
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C. Lamathe, The number of labeled k-arch graphs, Journal of Integer Sequences, Vol. 7 (2004), Article 04.3.1.
Saverio Caminiti and Emanuele G. Fusco, On the Number of Labeled k-arch Graphs, Journal of Integer Sequences, Vol 10 (2007), Article 07.7.5
C. Lamathe, The number of labeled k-arch graphs, Journal of Integer Sequences, Vol. 7 (2004), Article 04.3.1.
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MAPLE
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seq( (n*(n-1)/2)^(n-3), n=2..19 );
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CROSSREFS
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Cf. A098722, A098723, A098724
Sequence in context: A138913 A127636 A131311 this_sequence A078629 A012497 A012690
Adjacent sequences: A098718 A098719 A098720 this_sequence A098722 A098723 A098724
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KEYWORD
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easy,nonn
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AUTHOR
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Cedric Lamathe (lamathe(AT)loria.fr), Sep 30 2004
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