OFFSET
4,1
LINKS
FORMULA
a(n)=n^n-4*(n-1)^n+6*(n-2)^n-4*(n-3)^n+(n-4)^n, (n=4,5,...)
EXAMPLE
a(7)=109200
MAPLE
a:=n->n^n-4*(n-1)^n+6*(n-2)^n-4*(n-3)^n+(n-4)^n;
MATHEMATICA
Drop[Table[Sum[(-1)^k Binomial[4, k] (n-k)^n, {k, 0, 4}], {n, 1, 20}], 3] (* Geoffrey Critzer, Dec 23 2012 *)
CROSSREFS
KEYWORD
nonn
AUTHOR
Aleksandar M. Janjic and Milan Janjic, Feb 18 2007
STATUS
approved