A253380 Numbers k such that 17^k + 4 is prime.

0, 2, 6, 18, 7238

Offset

1,2

Comments

No further terms up to 10000.

No further terms up to 37200. - Michael S. Branicky, Mar 22 2023

Links

Table of n, a(n) for n=1..5.

Example

For k = 0: 17^0 + 4 = 5, which is prime, so 0 is a term of the sequence.
For k = 2: 17^2 + 4 = 293, which is prime, so 2 is a term of the sequence.

Mathematica

Select[Range@10^5, PrimeQ[17^# + 4] &] (* Michael De Vlieger, Jan 03 2015 *)

Prog

(PARI) for(n=0, 1e5, if(ispseudoprime(17^n+4), print1(n, ", ")))

Crossrefs

Corresponding sequences for k^n+4: A058958 (k=3), A124621 (k=5), A096305(k=7), A217384 (k=9), A137236 (k=13), A247166 (k=15), A243397 (k=19).

Sequence in context: A064535 A240643 A262971 * A128123 A382055 A227884

Adjacent sequences: A253377 A253378 A253379 * A253381 A253382 A253383

Keyword

nonn,more

Author

Felix Fröhlich, Dec 31 2014

Status

approved