A075898 Numbers k such that 3^k + k^2 is prime.

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

Links

Table of n, a(n) for n=1..10.

Lucas A. Brown, A075898.py

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

Adjacent sequences: A075895 A075896 A075897 * A075899 A075900 A075901

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