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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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10
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1, 1, 6, 100, 3375, 194481, 17210368, 2176782336, 373669453125, 83733937890625, 23762680013799936, 8335775831236199424, 3543686674874777831491, 1795856326022129150390625, 1069932053790720000000000000
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OFFSET
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2,3
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COMMENTS
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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. - Saverio Caminiti and Emanuele G. Fusco (fusco(AT)di.uniroma1.it), Sep 18 2007
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LINKS
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MAPLE
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seq( (n*(n-1)/2)^(n-3), n=2..19 );
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MATHEMATICA
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Table[Binomial[n, 2]^(n-3), {n, 2, 20}] (* Harvey P. Dale, Jan 25 2012 *)
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CROSSREFS
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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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STATUS
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approved
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