I was a bit bored, and came up with this conjecture - Euler’s unsolvability conjecture. If a problem that euler has tried to solve, but he could not, then that problem is unsolvable (by unolvable, either a analytic closed form solution does not exist, or if he was trying to find a polynomial solution to np problem). I know this is not a proper conjecture/or proper maths, but this community is closest to what i want to say.
Euler failed to prove fermats last theorem, but it was later proven to be true, so unfortunately your conjecture is false
but did euler really try hard enough? my conjecture leaves out just enough room in it’s current form to become unfalsifiable.
on a more serious note, at least 1 part of my reasoning was that someone will give examples of instances where euler was not successful, and the fact that we had to come up with a relatively recent solution, it really puts feathers to euler’s hat


