Can someone help me with this problem...I can get up to

lim as n--> infinity (n(n+1)(2n+1)) / (6n^4) and then im stuck..

Heres the question..Find the lim as n-->infinity of

sigma(with 'n' ontop of the sigma symbol; i=1 on the bottom)

of ...1/n[(i/n)^2)+1]

Thanks!