Are there other n (besides 1,3,9) such as 1 +2^n+4^n is prime ? > From: <vincenzo.librandi at tin.it> > Conjecture > If a(n) =1^n+2^n+4^n= prime number, > then > n is the > form > 3^h. > > Example: > For h=1, n=3, and 1^3+2^3+4^3=73 (prime) > > h=2, n=9, > and > 1^9+2^9+4^9=262657 (prime)