login
A075898
Numbers k such that 3^k + k^2 is prime.
2
2, 4, 10, 22, 40, 304, 1582, 3602, 46162, 127990
OFFSET
1,1
COMMENTS
a(9) > 20000. - Jon E. Schoenfield, Jan 14 2015
a(10) > 10^5. - Lucas A. Brown, Feb 11 2021
MATHEMATICA
Select[Range[10000], PrimeQ[3^# + #^2] &] (* Vincenzo Librandi, Oct 04 2012 *)
PROG
(Magma) [n: n in [0..1000] | IsPrime(3^n+n^2)]; // Vincenzo Librandi, Dec 16 2010
(PARI) is(n)=ispseudoprime(3^n+n^2) \\ Charles R Greathouse IV, Jun 12 2017
CROSSREFS
Cf. A075899 (for the corresponding primes).
Sequence in context: A023036 A263661 A005306 * A360631 A337654 A369491
KEYWORD
nonn,more
AUTHOR
Zak Seidov, Oct 17 2002
EXTENSIONS
a(6) from Vincenzo Librandi, Dec 16 2010
a(7) from D. S. McNeil, Dec 16 2010
a(8) from Vincenzo Librandi, Oct 04 2012
a(9) from Lucas A. Brown, Feb 11 2021
a(10) from Michael S. Branicky, Sep 07 2024
STATUS
approved