{"schema":"vela.problem-packet.v0.1","problem":888,"statement":"What is the size of the largest $A\\subseteq \\{1,\\ldots,n\\}$ such that if $a\\leq b\\leq c\\leq d\\in A$ are such that $abcd$ is a square then $ad=bc$?","status":"solved","seam":"raw","closureRoutes":[],"obligations":[],"attestations":[],"attempts":[],"velaLean":[],"oeis":[{"id":"A387584","name":"Size of largest subset of {1, ..., n} such that any 4 elements (a <= b <= c <= d) whose product is square implies a*d = b*c.","terms":"1,2,3,3,4,5,6,6,6,7,8,8,9,10,10,10,11,11,12,12,13,14,15,15,15,16,16,16,17,17,18,18,19,20,21,21,22,23,24,24,25,25,26,26,2","url":"https://oeis.org/A387584"}],"generated_note":"derived view; the signed event log is the source of truth (vela check / vela reproduce)"}