For which natural numbers $m,n$
$m^2+4n^2$ is prime
I tried to check it by cases
case 1: if $m$ and $n$ are even then the expression will be divisible by two, thus it's not prime.
case 2: If $m$ and $n$ are perfect square then this expression isn't prime, since it can be factored.
any hint will be appreciated
I wrote and ran some Mathematica code:
Running the code gives:
So, we can see that when we have a lot of solutions given in the form $\left(\text{m}^2+4\text{n}^2,\text{m},\text{n}\right)$ in between the following boundaries $0\le\text{m}\le10^2$ and $0\le\text{n}\le10^2$.