CGMO 2019 Problem 2

Find integers $a_1,a_2,\cdots,a_{18}$ , s.t. $a_1=1,a_2=2,a_{18}=2019$ , and for all $3\le k\le 18$ , there exists $1\le i<j<k$ with $a_k=a_i+a_j$ .