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

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

Offset

1,3

Comments

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

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

Links

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

Mathematica

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

Prog

(PARI) for(n=0, 10^5, if(ispseudoprime(19^n+4), print1(n, ", ")))
(Magma) [n: n in [0..1000] | IsPrime(19^n+4)]; // Vincenzo Librandi, Oct 16 2014

Crossrefs

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

Sequence in context: A228115 A033888 A141492 * A173350 A323203 A169634

Adjacent sequences: A243394 A243395 A243396 * A243398 A243399 A243400

Keyword

nonn,more

Author

Felix Fröhlich, Jun 04 2014

Extensions

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

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

Status

approved