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A243397
Numbers n such that 19^n+4 is prime.
2
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
No further terms up to 50000. - Michael S. Branicky, Oct 09 2024
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 A372943
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