Problem

Source: MEMO 2008, Single, Problem 1

Tags: inequalities, algebra unsolved, algebra



Let (an)n=1 be a sequence of integers with an<an+1,n1. For all quadruple (i,j,k,l) of indices such that 1i<jk<l and i+l=j+k we have the inequality ai+al>aj+ak. Determine the least possible value of a2008.