Let ${\left(a_n\right)}_{n\ge 1}$ be the sequence given by $a_1=1$ and $a_n=n^{a_{n-1}}$ for $n\ge 2$. In this paper, we show that the only solution of the equation$$a_1+\cdots +a_n=m^l$$is in positive integers $l\>1,m$ and $n$ is $m=n=1$.