Erdős Problem a Daythe open tracker

Erdős Problem #1204

OPENdatabase updated 2026-04-04

No proof or disproof is known, and it isn't known whether a finite computation could settle it.

What the community database records, not our verdict. erdosproblems.com no longer shows statuses (why).

A finite set `S` of natural numbers is *admissible* if it misses at least one residue class modulo every prime. A sequence \(0\leq a_1<\cdots <a_k\) is identified with the set of its values.

\(A(k)\): the least possible value of \(a_k\) over admissible sequences \(0\leq a_1<\cdots <a_k\). Any \(k\) primes larger than \(k\) form an admissible set, so `sInf` is a true minimum.

The least possible value of \(a_1+\cdots+a_k\) over admissible sequences \(0\leq a_1<\cdots <a_k\). As for `A`, the minimum exists.

We call a sequence of integers \(0\leq a_1<\cdots <a_k\) admissible if it is missing at least one congruence class modulo every prime \(p\). Let \(A(k)=\min a_k\). Estimate \(A(k)\) - in particular, is it true that \[A(k)\sim k\log k?\]
Statement as formalized in Formal Conjectures (Google DeepMind, Apache-2.0) · their label: research open · 4 further variants / known partial results in the Lean file. The authoritative wording is on erdosproblems.com/1204.
Prizenone
Topicsnumber theory
Statement in LeanFormal Conjectures
Solution in Leanno
OEISA008407, A023193, A135311
Original pageerdosproblems.com/1204
WORKING REPORT BY THIS SITE · JUL 29, 2026

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proved the residue-vector and reflection reductions, exhaustively verified \(A(k)\), \(B(k)\), and greedy \(B\)-optimality for \(1\leq k\leq22\), and derived conditional liminf constants \(1/2\) and \

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