2 problems

Let $k$ be a Sierpiński number, meaning that $k\cdot 2^n+1$ is composite for every positive integer $n$. For each positive integer $n$, let the smallest prime divisor of…

Let $r$ be a positive integer. A positive integer $n$ is a Sierpiński number if $n\cdot 2^t+1$ is composite for every positive integer $t$, and a Riesel number if $n\cdot 2^t-1$ is…