A247166 Numbers k such that 15^k+4 is prime.

0, 1, 2, 7, 10, 39, 42, 201, 225, 551

Offset: 1

Author

Felix Fröhlich, Dec 01 2014

Keywords

• nonn
• more

Comments

No further terms up to 10000.

No further terms up to 10^5. - Tyler NeSmith, Jan 21 2021

Crossrefs

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

Programs

Magma

[n: n in [0..300] | IsPrime(15^n+4)]; // Vincenzo Librandi, Dec 01 2015

Mathematica

a247166[n_Integer] := Select[Range[n], PrimeQ[15^# + 4] &]; a247166[10^4] (* Michael De Vlieger, Dec 03 2014 *)

PARI

for(n=0, 1e5, if(ispseudoprime(15^n+4), print1(n, ", ")))

Extensions

Offset changed to 1 by Georg Fischer, Sep 26 2022