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Erdős problem 1141

Are there infinitely many nn such that n−k2n-k^2 is prime for all kk with (n,k)=1(n,k)=1 and k2<nk^2 < n?

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FormalConjectures/ErdosProblems/

1141.lean

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Are there infinitely many nn such that n−k2n-k^2 is prime for all kk with (n,k)=1(n,k)=1 and k2<nk^2 < n?

In [Va99] it is asked whether 968968 is the largest integer with this property, but this is an error, since for example 968−9=7⋅137968-9=7\cdot 137.

The list of nn satisfying the given property is [A214583] in the OEIS. The largest known such nn is 17221722.

The answer is negative: [APSSV26b] proves a stronger finiteness theorem, deducing it from Pollack [Po17]. Oriike [Or26] formalised the deduction in Lean.

FormalConjectures/ErdosProblems/1141.leanErdos1141.erdos_11411 lineExact file
False ↔ Infinite ↑{n | Erdos1141.Erdos1141Prop n}
SolvedProof has a holelean4external proof

The proof uses `sorry`: part of the argument is written but not proved. Lean accepts the file; it does not accept the theorem.