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%I #16 Dec 15 2017 17:35:01
%S 3,17,593,32993,2097593,8589935681
%N Primes in the sequence n^2 + 2^n (A001580).
%C p and p^2 + 2^p are both prime only for p=3. All positive n satisfy the congruence n=3 (mod 6). - _Lekraj Beedassy_, Sep 07 2004
%C For values of n, see A064539. - _Lekraj Beedassy_, Jan 01 2007
%C The next term has 605 digits. - _Harvey P. Dale_, Jul 19 2017
%D J.-M. De Koninck & A. Mercier, 1001 Problemes en Theorie Classique Des Nombres,Problem 165 pp. 30; 160, Ellipses Paris 2004.
%e a(3) = 593 = 2^9 +9^2. a(4) = 32993= 2^15 + 15^2.
%t Select[Table[n^2+2^n,{n,1000}],PrimeQ] (* _Harvey P. Dale_, Jul 19 2017 *)
%o (PARI) for(n=1,10^7, if(isprime(n^2+2^n),print(n^2+2^n)))
%Y Subsequence of A094133.
%Y Cf. A001580, A075896.
%K nonn
%O 1,1
%A _Amarnath Murthy_, Apr 21 2001
%E More terms from _Jason Earls_, Aug 09 2001. Next term too large to include.
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