Runs of $>c_1\log x$ consecutive primes with all gaps $>c_2$: must they always exist? (Erdős #238)
Statement
Let $c_1,c_2>0$. Is it true that for every sufficiently large $x$ there exist more than $c_1\log x$ consecutive primes, all at most $x$, such that the difference between any two of them exceeds $c_2$? Equivalently: does there always exist a block of more than $c_1\log x$ consecutive primes $p_m,p_{m+1},\ldots\le x$ in which every gap $p_{i+1}-p_i>c_2$? The assertion is to hold for all pairs $c_1,c_2>0$.
Acceptance. FULLY RESOLVES: a complete proof that for every $c_1,c_2>0$ and all sufficiently large $x$ there exist more than $c_1\log x$ consecutive primes $\le x$ with all pairwise differences $>c_2$ — machine-checkable (Lean/Coq) preferred, otherwise a full written proof; OR a disproof exhibiting $c_1,c_2>0$ for which the property fails for arbitrarily large $x$. ADVANCES (each a complete proof, strictly beyond Erdős's small-$c_1$ result stated in the background): prove the conclusion for all $c_1$ below an explicit threshold larger than any previously admissible value, with the dependence on $c_2$ made explicit; or establish it for all $c_1>0$ under a clearly stated hypothesis (e.g. a form of Hardy–Littlewood); or prove a quantitative lower bound on the length of the longest such run in $[1,x]$ that grows strictly faster than the currently guaranteed $c_1\log x$. Deliver a machine-checkable or complete written proof.
Background
Posed by Erdős [Er55c, p.7]; listed as open on erdosproblems.com/238 (fetched 2026-07-21, status 'open'). Erdős [Er49c] proved the statement in the small-$c_1$ regime: for any $c_2>0$ there is some sufficiently small $c_1>0$ (depending on $c_2$) for which such runs of more than $c_1\log x$ well-separated consecutive primes exist for all large $x$. The open content is uniformity in $c_1$ — that the conclusion holds for every $c_1>0$, i.e. that one can find arbitrarily long runs (as a constant multiple of $\log x$) of consecutive primes all of whose gaps exceed a fixed $c_2$. The statement has a Lean formalization in the formal-conjectures project; no Erdős prize is attached. Attacker's tool: analytic results on the distribution of prime gaps and clusters (Erdős–Rankin and Maynard–Tao large-gap constructions, and counts of primes with prescribed gap patterns); computation can locate long runs of consecutive primes with all gaps $>c_2$ and measure their length against $c_1\log x$ to probe the conjectured constants.
References
| Ref | Source | Type |
|---|---|---|
| REF-01 | Erdős Problem #238 (T. F. Bloom) | website |
| REF-02 | Lean formalisation (formal-conjectures, Erdős #238) | website |
Investigations · 0
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