This means n = +/- sqrt a_k therefore k >1 must apply ? smilarly for a1 + a2 +........ak = n(1/a1 + 1/a2 +....1/ak)?
No it means that if you set then the left hand side equals and the right hand side is equal to , so the condition of the problem is satisfied by these values (at least it is when is a perfect square, otherwise the 's are not integers and we still need a solution).