[#P3052] Existence of the Mean Power Limit for Squarefree Gaps
Contents
Problem. Erdős Problem 145: Let $s_1 < s_2 < \cdots$ denote the sequence of squarefree positive integers, enumerated in increasing order. For each real number $x \geq 0$, let $A(x)$ be the set of indices $n$ such that $s_n \leq x$. For each real number $\alpha \geq 0$, consider the quantity \[ \frac{1}{x} \sum_{n \in A(x)} (s_{n+1} - s_n)^{\alpha} \] as $x \to \infty$. Does there exist, for every $\alpha \geq 0$, a real number $\beta$ such that this quantity converges to $\beta$ as $x \to \infty$? Equivalently, does the limit \[ \lim_{x \to \infty} \frac{1}{x} \sum_{s_n \leq x} (s_{n+1} - s_n)^{\alpha} \] exist for all $\alpha \geq 0$?
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Definitions and notation
1Context
This problem concerns the distribution of gaps between consecutive squarefree numbers. A squarefree number is a positive integer that is not divisible by any perfect square other than $1$. Erdős originally posed this question about whether the mean value of powers of gaps between consecutive squarefree numbers has a limiting value. Partial results are known: the limit exists for $0 \leq \alpha \leq 2$ (Erdős, 1951), for $0 \leq \alpha \leq 3$ (Hooley, 1973), and for $0 \leq \alpha \leq 11/3$ (Greaves, Harman, and Huxley, 1997).
2Problem setup
Definition 1 (A positive integer $n$). A positive integer $n$ is called squarefree if no prime squared divides $n$, or equivalently, if in the prime factorization of $n$, every prime appears with exponent at most $1$.
Definition 2 (The sequence $(s_n)_{n \geq 1}$ of squarefree numbers). The sequence $(s_n)_{n \geq 1}$ of squarefree numbers is the strictly increasing enumeration of all squarefree positive integers.
Remark 1. For a real number $x \geq 0$, the set $A(x)$ consists of all indices $n$ such that $s_n \leq x$.
Definition 3 (For a real number $\alpha \geq 0$ and a real number $x > 0$, the expression $\frac{1}{x} \sum_{n \in A(x)} (s_{n+1} - s_n)^{\alpha}$). For a real number $\alpha \geq 0$ and a real number $x > 0$, the expression $\frac{1}{x} \sum_{n \in A(x)} (s_{n+1} - s_n)^{\alpha}$ is the average of the $\alpha$th powers of gaps between consecutive squarefree numbers, where the average is taken over all gaps starting at squarefree numbers up to $x$.
3What counts as a solution
- Give a rigorous proof or counterexample that completely resolves this statement: Erdős Problem 145: Let $s_1 < s_2 < \cdots$ denote the sequence of squarefree positive integers, enumerated in increasing order. For each real number $x \geq 0$, let $A(x)$ be the set of indices $n$ such that $s_n \leq x$. For each real number $\alpha \geq 0$, consider the quantity \[ \frac{1}{x} \sum_{n \in A(x)} (s_{n+1} - s_n)^{\alpha} \] as $x \to \infty$. Does there exist, for every $\alpha \geq 0$, a real number $\beta$ such that this quantity converges to $\beta$ as $x \to \infty$? Equivalently, does the limit \[ \lim_{x \to \infty} \frac{1}{x} \sum_{s_n \leq x} (s_{n+1} - s_n)^{\alpha} \] exist for all $\alpha \geq 0$?
1Status
Saved packet · July 31, 2026
Saved packet status (Current status and unresolved remainder). OPEN as of 2026-07-31. The maintained Erdős Problems database at commit 8138974387d9030542daabe67faaa33eff9356f8 lists Problem 145 as open. The unresolved remainder is the full displayed statement. Give a rigorous proof or counterexample that completely resolves this statement: Erdős Problem 145: Let $s_1 < s_2 < \cdots$ denote the sequence of squarefree positive integers, enumerated in increasing order. For each real number $x \geq 0$, let $A(x)$ be the set of indices $n$ such that $s_n \leq x$. For each real number $\alpha \geq 0$, consider the quantity \[ \frac{1}{x} \sum_{n \in A(x)} (s_{n+1} - s_n)^{\alpha} \] as $x \to \infty$. Does there exist, for every $\alpha \geq 0$, a real number $\beta$ such that this quantity converges to $\beta$ as $x \to \infty$? Equivalently, does the limit \[ \lim_{x \to \infty} \frac{1}{x} \sum_{s_n \leq x} (s_{n+1} - s_n)^{\alpha} \] exist for all $\alpha \geq 0$?[1]
1Packet records
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Notes and companion material
Original intake status. OPEN as of 2026-07-31. The maintained Erdős Problems database at commit 8138974387d9030542daabe67faaa33eff9356f8 lists Problem 145 as open. The unresolved remainder is the full displayed statement.
- The maintained database entry for Erdős Problem 145 was open at commit 8138974387d9030542daabe67faaa33eff9356f8.
- The pinned Formal Conjectures declaration was matched by problem number and source locator.
- The controlled TheoremDB source corpus was checked for an already published record with the same slug.
How the 2 records connect
ProblemExistence of the Mean Power Limit for Squarefree Gaps
All 1 recorded relations between these records and the problem
2See also
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Cite this problem statement
Cite the original sources separately.
“Existence of the Mean Power Limit for Squarefree Gaps.” TheoremDB. P3052. Problem statement; statement text SHA-256 c88a484ab4317cad8ffbc7cdd5ff64acd81b0060cf8b44a405060c1e6a5b217a. https://theoremdb.org/statement/?ref=P3052
@misc{theoremdb-problem-c88a484ab4317cad8ffbc7cdd5ff64acd81b0060cf8b44a405060c1e6a5b217a,
title = {{Existence of the Mean Power Limit for Squarefree Gaps}},
howpublished = {TheoremDB},
note = {Problem statement; statement text SHA-256 c88a484ab4317cad8ffbc7cdd5ff64acd81b0060cf8b44a405060c1e6a5b217a},
url = {https://theoremdb.org/statement/?ref=P3052}
}Plain text: Built Markdown snapshot
This problem includes 2 records joined by 1 typed links, sourced from erdosproblems.com[1], current as of July 31, 2026.
1References
- Packet source. Erdős Problems database, Problem 145, maintained status record. Erdős Problems record 145, checked 2026-08-01. Problem 145; status field and linked bibliography. ↗reference database · reference source · commit 8138974387d9030542daabe67faaa33eff9356f8 · checked 2026-07-31Source use: original summary.Records the current open status and links the literature attached to this exact numbered problem.Also cited at Problem 145; status snapshot 8138974387d9030542daabe67faaa33eff9356f8.Also cited at See dataset.references[0] for the exact external source and locator.Also cited at Editorial research route recorded 2026-07-31.Source used to formulate or check the problem record.Source used to assess the problem's recorded status.For Existence of the Mean Power Limit for Squarefree Gaps: Records the current open status and links the literature attached to this exact numbered problem.Source named by the research packet.
- Erdős problem database, data/problems.yaml, commit 8138974387d9030542daabe67faaa33eff9356f8. Problem 145 entry in data/problems.yaml. ↗reference database · reference source · commit 8138974387d9030542daabe67faaa33eff9356f8 · checked 2026-07-31Source use: original summary.Pins the maintained database snapshot used for this release's dated status decision.Source used to assess the problem's recorded status.For Existence of the Mean Power Limit for Squarefree Gaps: Pins the maintained database snapshot used for this release's dated status decision.
- Google DeepMind, Formal Conjectures, formal statement for Erdős Problem 145. GitHub commit bb1c69dab14ad895ac1ccdb7b0c0e0a67c8eb3e1. FormalConjectures/ErdosProblems/145.lean:L46; theorem erdos_145; commit bb1c69dab14ad895ac1ccdb7b0c0e0a67c8eb3e1. ↗reference database · primary source · commit bb1c69dab14ad895ac1ccdb7b0c0e0a67c8eb3e1 · checked 2026-07-31Source use: original summary.Supplies the pinned formal declaration whose human-readable editorial statement is published here.Source used to assess the problem's recorded status.For Existence of the Mean Power Limit for Squarefree Gaps: Supplies the pinned formal declaration whose human-readable editorial statement is published here.
Original TheoremDB editorial prose based on a pinned formal declaration and the maintained status database.
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