---
tag: 7Z5NB3H0ZS
kind: concept
name: Erdős–Oler conjecture
sources:
  - wikipedia: en:183091@r1376385932
    locator: List of unsolved problems in mathematics, section Unsolved problems > Geometry > Covering and packing
    note: adopted
    mention: wikipedia://en/183091#0FJI
    sections: [Summary]
inventory: [3JTAPQBWN8]
---

## Summary

- The Erdős–Oler conjecture: when $n$ is a triangular number, packing $n-1$ circles in an equilateral triangle requires a triangle of the same size as packing $n$ circles.