  Let $n \geqslant 4$. In this article, we will determine the asymptotic
behaviour of the size of the set $M(B)$ of integral points $(a_{0}:... :a_{n})$
on the hyperplane $\sum_{i=0}^{n}X_{i}=0$ in $\mathbf{P}^{n}$ such that $a_{i}$
is squareful (an integer $a$ is called squareful if the exponent of each prime
divisor of $a$ is at least two), non-zero and $|a_{i}|\leq B$ for each $i \in
\{0,...,n\}$, when $B$ goes to infinity. For this, I will use the classical
Hardy-Littlewood method. The result obtained supports a possible generalization
of the Brauer-Manin program to Fano orbifolds.
