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A061119 Primes in the sequence n^2 + 2^n (A001580). 9

%I

%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

%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.

%o (PARI) for(n=1,10^7, if(isprime(n^2+2^n),print(n^2+2^n)))

%Y Cf. A001580, A075896.

%K nonn

%O 1,1

%A _Amarnath Murthy_, Apr 21 2001

%E More terms from Jason Earls (zevi_35711(AT)yahoo.com), Aug 09 2001. Next term too large to include.

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Last modified December 4 17:23 EST 2016. Contains 278751 sequences.