In the book Number Theory: An Approach through History by André Weil, a reference is given on page 42 :
"J. E. Hofmann, Neues über Fermats zahlentheoretische Herausforderingen von 1657, Abh.d.preuss.Akad.d.Wiss. 1943-1944, Nr.9, pp. 41- 47."
I'm looking for the above paper, either downloadable or purchasable copy.
Any help will be greatly appreciated.