1969 problem 1

Stream: IMO-grand-challenge

[Kevin Lacker]

Okay, I wrote up a pull request formalizing 1969 problem 1. https://github.com/leanprover-community/mathlib/pull/4261 I'd love to get someone to take a look!

[Kevin Lacker]

FYI the problem is: Prove that there are infinitely many natural numbers $a$ with the following property: the number $z = n^4 + a$ is not prime for any natural number $n$ . I chose this one because it seemed easy.