OFFSET
1,3
COMMENTS
Theorem A, p. 3, of Dong.
LINKS
Guanghua Dong, Han Ren, Ning Wang, Yuanqiu Huang, Lower bound on the number of the maximum genus embedding of K_{n,n}, arXiv:1203.0855 [math.CO]
FORMULA
For n odd, a(n) = 2^((n-1)/2)*(n-2)!!^n*(n-1)!^n; otherwise a(n) = 0.
PROG
(PARI) a(n)=if(n%2, 2^(n\2)*prod(i=1, n\2, 2*i-1)^n*(n-1)!^n, 0) \\ Charles R Greathouse IV, Jun 19 2013
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Jonathan Vos Post, Mar 06 2012
EXTENSIONS
Terms corrected by Charles R Greathouse IV, Jun 19 2013
STATUS
approved