OFFSET
1,3
LINKS
Alois P. Heinz, Table of n, a(n) for n = 1..228
Eric Weisstein's World of Mathematics, Complete Bipartite Graph
Wikipedia, Chromatic Polynomial
FORMULA
a(n) = 1/n * Sum_{j=1..n} (n-j)^n * Stirling2(n,j) * Product_{i=0..j-1} (n-i).
a(n) = 1/n * A212085(n,n).
a(n) ~ c * d^n * n^(2*n-1) / exp(2*n), where d = 3.42422933454838937778530870500341391459244769750638251404159... and c = 0.646741403357125093928623036806787050141001... . - Vaclav Kotesovec, Feb 18 2017
MAPLE
a:= n-> add(Stirling2(n, j)*mul(n-i, i=0..j-1)*(n-j)^n, j=1..n)/n:
seq(a(n), n=1..20);
CROSSREFS
KEYWORD
nonn
AUTHOR
Alois P. Heinz, Feb 09 2017
STATUS
approved