We consider the problem of non-existence of solutions for the following Hénon-Lane-Emden system −∆u = |x|v in R , −∆v = |x|u in R , when pq > 1, p, q, a, b ≥ 0, and (p, q) are under the critical hyperbola, i.e. N+a p+1 + N+b q+1 > N − 2. We show that there is no positive bounded solution in dimension N = 3, extending a result established recently by Phan-Souplet in the scalar case. This solve...