title: "IMO 1984 LL SPA53" description: "Find a sequence of natural numbers ai such that ai = i+4" date: "2026-05-29T11:51:44+07:00" tags: ["imo", "longlist", "mathematics", "olympiad"] categories: ["mathematics"] year: 1984 type: "longlist" origin: "SPA" weight: 198400053 draft: false

IMO 1984 LL SPA53

Origin: SPA

Problem

Find a sequence of natural numbers ai such that ai = i+4 r=1 dr, where dr ̸= ds for r ̸= s and dr divides ai.