Proposed by Christian Bessiere
This problem, posed first by G.L. Honaker, is to put a queen and the $n^2$ numbers $1,…,n^2$, on a $n \times n$ chessboard so that:
Note that 1 is not prime, and that the queen does not attack its own cell.
A 6x6 chessboard without free primes (the queen is on the cell containing 33):