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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 (list; graph; refs; listen; history; text; internal format)
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

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Last modified December 1 16:44 EST 2021. Contains 349430 sequences. (Running on oeis4.)