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F(n)*2^n - 1 is prime, where F(n) is the n-th Fibonacci number.
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%I #4 Sep 20 2014 13:48:08

%S 2,4,7,24,25,47,57,60,241,391,1252,1391,2340,4062

%N F(n)*2^n - 1 is prime, where F(n) is the n-th Fibonacci number.

%t Do[ If[ PrimeQ[ Fibonacci[ n ]*2^n - 1 ], Print[ n ] ], {n, 1, 3000} ]

%t Select[Range[5000],PrimeQ[Fibonacci[#]2^#-1]&] (* _Harvey P. Dale_, Sep 20 2014 *)

%K nonn

%O 1,1

%A _Robert G. Wilson v_, Feb 05 2001

%E a(14) added by _Harvey P. Dale_, Sep 20 2014