Let A={1, a_1, a_2 ….. a_18, 77} be a set of integers with 1<a_1<a_2<….<a_18<77. Let the set A+A={x+y: x, y ∈ A} contain exactly 39 elements. Then,…

Let $\displaystyle A=\left\{1, a_1, a_2 \ldots . . a_{18}, 77\right\}$ be a set of integers with $\displaystyle 1<a_1<a_2<\ldots .<a_{18}<77$. Let the set $\displaystyle A+A=\{x+y: x, y \in A\}$ contain exactly $\displaystyle 39$ elements. Then, the value of $\displaystyle a_1+a_2+\ldots .+a_{18}$ is equal to \_\_\_\_.