A104003 (3/4)*(27*n^2-137*n+180)*n^(n-6)*(2*n-6)!/(n-3)!.

6, 306, 29700, 4798080, 1178634240, 412483246560, 195891696000000, 121597736131872000, 95776583838282547200, 93456899248404570278400, 110767880742079885561036800, 156855803355661410000000000000, 261695274412151118929854464000000, 508262037307349207558239385902080000

Offset

4,1

References

Lando S. K. and Zvonkine D., Counting ramified coverings and intersection theory on Hurwitz spaces I (cohomological identities). Moscow Mathematical Journal, vol. 7 (2007), no. 1, 85-107.

Links

Table of n, a(n) for n=4..17.

D. Zvonkine, Home Page

Prog

(PARI) a(n)=(3/4)*(27*n^2-137*n+180)*n^(n-6)*(2*n-6)!/(n-3)! \\ Charles R Greathouse IV, May 01 2020

Crossrefs

Sequence in context: A221850 A229148 A333482 * A280215 A015103 A282373

Adjacent sequences: A104000 A104001 A104002 * A104004 A104005 A104006

Keyword

nonn,easy

Author

N. J. A. Sloane, Jan 30 2008

Status

approved