Let n>2 be a positive integer. Consider all numbers S of the form
\begin{align*} S= a_1 a_2 + a_2 a_3 + \ldots + a_{k-1} a_k \end{align*}
with k>1 and ai begin positive integers such that a1+a2+…+ak=n. Determine all the numbers that can be represented in the given form. algebra unsolvedBalkan Mathematics Olympiad