Question : Write an expression for: 11^2 + 12^2 + 13^2 + ... + n^2

The previous question had the expression:

1+2^2 = n x (n+1) x (2n+1) /6

This expression is a quick way to add square numbers together starting at one. I've got to find a similar expression which adds square numbers together, but the pattern must start at 11^2.