A243397 Numbers n such that 19^n+4 is prime.

0, 1, 3, 21, 145, 273, 1425, 9613, 15711, 18445

Offset: 1

Author

Felix Fröhlich, Jun 04 2014

Keywords

• nonn
• more

Comments

No further terms up to 20000. - Felix Fröhlich, Oct 29 2014

No further terms up to 24000. - Felix Fröhlich, Jan 22 2015

No further terms up to 50000. - Michael S. Branicky, Oct 09 2024

Crossrefs

Corresponding sequences for k^n+4: A058958 (k=3), A124621 (k=5), A096305 (k=7), A217384 (k=9), A137236 (k=13).

Programs

Magma

[n: n in [0..1000] | IsPrime(19^n+4)]; // Vincenzo Librandi, Oct 16 2014

Mathematica

Select[Range[0, 10000], PrimeQ[19^# + 4] &] (* Vincenzo Librandi, Oct 16 2014 *)

PARI

for(n=0, 10^5, if(ispseudoprime(19^n+4), print1(n, ", ")))

Extensions

a(1)-a(2) prepended by N. J. A. Sloane, Jun 18 2014

a(9)-a(10) from Felix Fröhlich, Oct 16 2014