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%I #17 Sep 08 2022 08:45:11
%S 0,1,3,9
%N Numbers n such that 2^n + n and 2^n - n are noncomposite.
%C Conjecture: sequence is finite.
%C No more terms < 88075. - _David Wasserman_, Jul 20 2005
%e 9 is a member as 2^9 + 9 = 521 and 2^9 - 9 = 503 are primes.
%t Join[{0, 1}, Select[Range[1000], PrimeQ[2^# + #] && PrimeQ[2^# -#] &]] (* _Vincenzo Librandi_, Dec 08 2015 *)
%o (Magma) [0,1] cat [n: n in [0..1000] | IsPrime(2^n+n) and IsPrime(2^n-n)]; // _Vincenzo Librandi_, Dec 08 2015
%Y Cf. A048744, A052007.
%K more,nonn
%O 1,3
%A _Amarnath Murthy_, Sep 25 2003
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