

A209201


A lower bound on the number of the distinct maximum genus embedding of the complete bipartite graph K(n,n).


0




OFFSET

1,3


COMMENTS

Theorem A, p. 3, of Dong.


LINKS

Table of n, a(n) for n=1..10.
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^((n1)/2)*(n2)!!^n*(n1)!^n; otherwise a(n) = 0.


PROG

(PARI) a(n)=if(n%2, 2^(n\2)*prod(i=1, n\2, 2*i1)^n*(n1)!^n, 0) \\ Charles R Greathouse IV, Jun 19 2013


CROSSREFS

Cf. A000142 (factorial numbers), A001147 (double factorial numbers).
Sequence in context: A173436 A081263 A265491 * A050467 A008835 A040259
Adjacent sequences: A209198 A209199 A209200 * A209202 A209203 A209204


KEYWORD

nonn,easy


AUTHOR

Jonathan Vos Post, Mar 06 2012


EXTENSIONS

Terms corrected by Charles R Greathouse IV, Jun 19 2013


STATUS

approved



