Complete characterization of $2$-near perfect numbers with exactly 2 prime factors

Richard Fearon, Henry Foushee, Benjamin Porosoff +3

Let $\sigma (n)$ be the sum of the positive divisors of $n$. A positive integer $n$ is said to be $2$-near perfect when $\sigma (n)=2n+d_1+d_2$, where $d_1$ and $d_2$ are distinct positive div…