Multi-target hyperbolic sieves and elliptic trace obstructions

Pantelimon Stănică, Erik Mulder, Markus Hittmeir

Let $N=pq$ be a product of two primes, and let $\ell$ be an odd prime not dividing $N$. For $a\in {\mathbb{F}}_{\ell }^{\ast }$, the set \[ H_a(N;\ell)=\{ax+Nx^{-1}:x\in\mathbb F_\ell^*\} \] co…