OFFSET
0,4
FORMULA
a(i)=0, i=0, 1, 2; a(n)= (n^2)*(n+1)^(n-2), n >= 3.
E.g.f.: -x*(1+4*x)/2 + (W(-x)^2)*(1-W(-x))/((1+W(-x))*x*2), W(x) principal branch of Lambert's function.
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Wolfdieter Lang Jun 20 2000
STATUS
approved