PPL 043 / 177 permanent IDsPrize Problem Ledger · PPLChecked 2026.07.26
Prize Problem LedgerErdősPPL 043Erdős Problem #142

Permanent problem IDPPL 043

Verified openErdősconjecture

Additive combinatorics

Erdős Problem #142

Let r_k(N) be the largest possible size of a subset of {1,…,N} that does not contain any non-trivial k-term arithmetic progression. Prove an asymptotic formula for r_k(N).

additive combinatoricsarithmetic progressions
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The problem

Let r_k(N) be the largest possible size of a subset of {1,…,N} that does not contain any non-trivial k-term arithmetic progression. Prove an asymptotic formula for r_k(N).

Open since1980earliest source
Last checked2026.07.26Catalog verification
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Reward offers

Offer 01$10000Paul Erdős / Combinatorics Foundation
Documented

A solution must appear in a reputable journal, with documentation that Erdős offered the displayed amount. Claims are administered by the Combinatorics Foundation; erdosproblems.com does not pay awards.

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Sources & reading