A247166 - OEIS

%I #48 Sep 26 2022 05:28:33

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

%N Numbers k such that 15^k+4 is prime.

%C No further terms up to 10000.

%C No further terms up to 10^5. - _Tyler NeSmith_, Jan 21 2021

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

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

%o (Magma) [n: n in [0..300] | IsPrime(15^n+4)]; // _Vincenzo Librandi_, Dec 01 2015

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

%K nonn,more

%O 1,3

%A _Felix Fröhlich_, Dec 01 2014

%E Offset changed to 1 by _Georg Fischer_, Sep 26 2022