{
  "domain": "mathematics",
  "topics": [
    "number-theory"
  ],
  "type": "construction",
  "also": [
    "proof"
  ],
  "source": {
    "key": "erdos",
    "name": "Erdős Problems",
    "url": "https://www.erdosproblems.com/647",
    "id": "647",
    "curator": "Thomas Bloom",
    "poser": "Paul Erdős and John Selfridge",
    "status": "open, £25 prize",
    "as_of": "2026-10-20",
    "prize": "£25",
    "catalog": "0521c19bbd38"
  },
  "review": true,
  "approval": "first-time"
}