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Numbers n with property that (5^n + 2^n - 1)/12 is prime.
0

%I #2 Mar 30 2012 17:26:28

%S 3,5,7,15,65,105,135,155,235,249

%N Numbers n with property that (5^n + 2^n - 1)/12 is prime.

%e Corresponding primes are: 11, 263, 6521, 2543134241,

%e 225875452601146757084886003255695202165296363,

%e 2054325274013051576593043138757255806440645138498014683534338706479543763.

%e Other terms are too large to be presented.

%Y Cf. A155588 5^n+2^n-1.

%K nonn

%O 1,1

%A _Zak Seidov_, Jan 27 2009