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Research notes on every problem, and a library of the papers behind them. Built from the open erdos repository.

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Claim. Let p1<p2<⋯p_1<p_2<\cdots be the primes, with the convention p0=1p_0=1, under which n=1n=1 lies in [p0,p1)[p_0,p_1) and counts; the formal-conjectures statement adopts the same convention. If pk−1≤n<pkp_{k-1}\le n<p_k and every prime dividing n!+1n!+1 is pkp_k or pk+1p_{k+1}, then n≤5n\le5; so n=1,2,3,4,5n=1,2,3,4,5 are the only such nn, and Problem 1058 is answered affirmatively: there are only finitely many. This is the Theorem of F. Luca, On a conjecture of Erdős and Stewart, Math. Comp. 70 (2001), no. 234, 893–896, received 1999-01-04 and published electronically 2000-03-08, the date this page carries; the source card is luca_2001_conjecture_erdos_stewart. The conjecture it proves is the one Guy reports as Erdős and Stewart's in Problem A2 of Unsolved problems in number theory.

Method. A 22-adic lower bound for linear forms in two logarithms (Bugeaud–Laurent), applied to ord⁡2(n!)=ord⁡2(pkapk+1b−1)\operatorname{ord}_2(n!)= \operatorname{ord}_2(p_k^ap_{k+1}^b-1), gives n<7 242 116n<7\,242\,116 (so pk+1<7.5⋅106p_{k+1}<7.5\cdot10^6); a computer search over cubic residues modulo the primes q≤193q\le193 with q≡1(mod3)q\equiv1\pmod 3 forces 3∣a3\mid a and 3∣b3\mid b in any remaining solution, which the Erdős–Obláth theorem on xp±yp=n!x^p\pm y^p=n! excludes; a second computation disposes of n≤193n\le193. No independent check of the proof is recorded.

Acceptance. The paper is refereed: Math. Comp. 70 (2001), no. 234. The site's curator, Thomas Bloom, marks Problem 1058 proved and credits Luca's paper. The formal-conjectures statement for Problem 1058 is closed by sorry but carries a formal-proof attribute pointing at the Lean 4 file linked above, which declares itself a formalization of Luca's solution (informal author Florian Luca; formal authors recorded as the AI systems Codex and GPT-5.6 Sol) and proves that nn is a solution exactly when n∈{1,2,3,4,5}n\in\{1,2,3,4,5\}. That file is linked as the claimant's formalization; this corpus has not built or audited it, so it is not listed as formalized evidence.

Depends on. No other wiki page; the claim rests on the cited paper.