A098722 a(n) = C(n, 3)^(n-4).

1, 1, 10, 400, 42875, 9834496, 4182119424, 2985984000000, 3329565857578125, 5487587353600000000, 12802485663117464444416, 40833239547181264169598976, 173031575921620011303271484375, 951166013805414055936000000000000

Offset

3,3

Comments

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 3-arch graphs on n nodes. The correct sequence is given in our paper.

Links

Table of n, a(n) for n=3..16.

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.

B. Leclerc, Graphes d'arches, Math. Sci. Hum. 157 (2002), 27-48.

Maple

with(combinat); seq( binomial(n, 3)^(n-4), n=3..19 );

Crossrefs

Cf. A098721, A098723, A098724.

Sequence in context: A013406 A183487 A172505 * A162677 A041767 A130557

Adjacent sequences: A098719 A098720 A098721 * A098723 A098724 A098725

Keyword

easy,nonn

Author

Cedric Lamathe (lamathe(AT)loria.fr), Sep 30 2004

Status

approved