OFFSET
0,5
FORMULA
a(i)=0, i=0..3; a(n)= (n^3)*(n+1)^(n-3), n >= 4.
E.g.f.: -x*(3+16*x+54*x^2)/12+(W(-x)^2)*(3-7*W(-x)+2*W(-x)^2)/ (12*(1+W(-x))*x), W(x) principal branch of Lambert's function.
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Wolfdieter Lang Jun 20 2000
STATUS
approved