## Problem of the Week 1218## A Prime-Sum CircleArrange the numbers 1, 2, 3, ..., 20 in a circle so that the sum of any two neighboring numbers is prime. Extra Credit. Resolve this with 20 replaced by n.
Source: Inspired by G. Hamilton, K.S. Kedlaya, and H. Picciotto, Square-sum pair partitions, |

January 2016