|
%I #38 Oct 10 2022 07:56:48
%S 2,4,10,22,40,304,1582,3602,46162
%N Numbers k such that 3^k + k^2 is prime.
%C a(9) > 20000. - _Jon E. Schoenfield_, Jan 14 2015
%C a(10) > 10^5. - _Lucas A. Brown_, Feb 11 2021
%H Lucas A. Brown, <a href="https://github.com/lucasaugustus/oeis/blob/main/A075898.py">A075898.py</a>
%t Select[Range[10000], PrimeQ[3^# + #^2] &] (* _Vincenzo Librandi_, Oct 04 2012 *)
%o (Magma) [n: n in [0..1000] | IsPrime(3^n+n^2)]; // _Vincenzo Librandi_, Dec 16 2010
%o (PARI) is(n)=ispseudoprime(3^n+n^2) \\ _Charles R Greathouse IV_, Jun 12 2017
%Y Cf. A075899 (for the corresponding primes).
%K nonn,more
%O 1,1
%A _Zak Seidov_, Oct 17 2002
%E a(6) from _Vincenzo Librandi_, Dec 16 2010
%E a(7) from _D. S. McNeil_, Dec 16 2010
%E a(8) from _Vincenzo Librandi_, Oct 04 2012
%E a(9) from _Lucas A. Brown_, Feb 11 2021
| 