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⇱ Erdős Problems


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Revision history of 1141. All highlighted changes are compared to the current version.

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Are there infinitely many $n$ such that $n-k^2$ is prime for all $k$ with $(n,k)=1$ and $k^2<n$?
In [Va99] it is asked whether $968$ is the largest integer with this property, but this is an error, since for example $968-9=7\cdot 137$.

The list of $n$ satisfying the given property is A214583 in the OEIS. The largest known such $n$ is $1722$.

ChatGPT and Tang have shown that the number of such $n$ in $[1,N]$ is at most $N^{1/2+o(1)}$.

An internal OpenAI model (see [APSSV26b]) has resolved this, proving that for any integer $a\geq 1$ there are only finitely many $n$ such that $n-ak^2$ is prime for all $k$ with $(k,n)=1$ and $ak^2<n$, deducing this from a result of Pollack [Po17].

See also [1140] and [1142].

2026-04-09 09:09:38

Are there infinitely many $n$ such that $n-k^2$ is prime for all $k$ with $(n,k)=1$ and $k^2<n$?
In [Va99] it is asked whether $968$ is the largest integer with this property, but this is an error, since for example $968-9=7\cdot 137$.

The list of $n$ satisfying the given property is A214583 in the OEIS. The largest known such $n$ is $1722$.

ChatGPT and Tang have shown that the number of such $n$ in $[1,N]$ is at most $N^{1/2+o(1)}$.

See also [1140] and [1142].