OFFSET
3,1
COMMENTS
The principal ratio of a strongly connected digraph is the ratio of largest to smallest entries in the stationary distribution of a simple random walk on that digraph.
LINKS
S. Aksoy, F. Chung, X. Peng, Extreme values of the stationary distribution of random walks on directed graphs, arXiv:1602.01162 [math.CO], 2016.
S. Aksoy, F. Chung, X. Peng, Extreme values of the stationary distribution of random walks on directed graphs, Advances in Applied Mathematics, 81:128--155, 2016.
FORMULA
a(n) = (2/3) * (n-1)! * ( n/(n-1) + (1/(n-1)!) * Sum_{i=1..n-3} i! ).
a(n) = 2 * A056199(n-1). - Alois P. Heinz, Aug 11 2019
PROG
(PARI) a(n) = (2/3) * (n-1)! * ( n/(n-1) + (1/(n-1)!) * sum(i=1, n-3, i!)); \\ Michel Marcus, Aug 11 2019
CROSSREFS
KEYWORD
nonn
AUTHOR
Sinan G. Aksoy, Aug 08 2019
STATUS
approved