2 problems

For each square-free positive integer $d$, let $\mathcal F$ be the set of parameters satisfying the necessary local conditions for solubility of the negative Pell equation, and def…

Let $d'$ range over square-free positive integers, and let $\mathcal F$ be the set of square-free positive integers all of whose odd prime divisors are congruent to $1\pmod 4$. Def…